freethinker
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C2 noun /ˈfriːˌθɪŋkər/

freethinker

自由思想家
Meaning
A person who forms opinions based on reason and independent thought rather than tradition or authority.
Example
Voltaire was considered a great freethinker of his time.
ヴォルテールは彼の時代の偉大な自由思想家と見なされていました。
C1 noun /faɪˈnælɪti/

finality

決定的な性質
Meaning
the quality of being final or irreversible; a sense of conclusiveness
Example
The judge's decision gave the case a sense of finality.
裁判官の決定はその事件に決定的な感覚を与えた。
B1 noun /ˈfeɪvər/

favor

お願い
Meaning
An act of kindness or approval.
Example
She asked him for a small favor.
彼女は彼に小さなお願いをした。
A1 adjective /ˈfʌn.i/

Funny

面白い; 変な; おかしい;
Meaning
humorous; strange; amusing;
Example
He told a funny joke that made everyone laugh.
彼はみんなを笑わせた面白いジョークを言いました。
B1 verb /fəʊld/

fold

Meaning
to bend something, especially paper or cloth, so that one part covers another
Example
She folded the letter neatly before placing it in the envelope.
B2 adjective /fɔːrˈsiːəbl/

foreseeable

予測可能な
Meaning
Able to be predicted or expected in advance
Example
The company is unlikely to make changes in the foreseeable future.
その会社は予測可能な未来において変化を起こす可能性は低い。
A2 noun /ˈfer.i.teɪl/

Fairy-tale

おとぎ話
Meaning
a children's story about magical and imaginary beings and lands
Example
Children love listening to fairy-tales before bedtime.
子供たちは寝る前におとぎ話を聞くのが大好きです。
B2 adjective, noun, verb /faʊl/

foul

Meaning
offensive to the senses; dirty or unpleasant; in sports, an unfair or illegal act
Example
The player was penalized for committing a foul.
C2 adjective /fəˈlɪsɪtəs/

felicitous

適切な、ふさわしい、または楽しい; 幸運や幸福で特徴付けられる
Meaning
well-chosen, appropriate, or pleasing; marked by good fortune or happiness
Example
She made a felicitous remark that lightened the mood.
彼女は気分を軽くする適切なコメントをしました。
B2 adverb /ˈfɜ:rmli/

Firmly

しっかりと
Meaning
in a strong, steady, and unwavering manner
Example
She firmly believed in her decision.
彼女は自分の決定に固く信じていた。
C2 noun /ˈfæn.feər/

fanfare

大々的な展示, 宣伝
Meaning
a short ceremonial tune or display of publicity to attract attention
Example
The new product was launched with much fanfare.
新しい製品は盛大なファンファーレで発売されました。
B2 adjective /ˈflʌfi/

fluffy

幸せ
Meaning
soft, light, and airy in texture
Example
She baked a fluffy cake for the party.
彼女は賞を受け取ったとき、幸せを隠すことができませんでした。
C1 adjective /ˈfliː.tɪŋ/

fleeting

儚い
Meaning
Lasting for a very short time; passing quickly.
Example
Happiness can be fleeting, so cherish every moment.
幸せは儚いものである可能性があるので、すべての瞬間を大切にしてください。
C1 noun /ˈfɔːrsəm/

foursome

四人組
Meaning
a group of four people or things, especially in games or social activities
Example
The foursome enjoyed a game of golf together.
四人組は一緒にゴルフを楽しみました。
B2 noun fɪkst ˈɪnkʌm

fixed income

固定収入
Meaning
Investment that provides a return in the form of fixed periodic payments.
Example
Fixed income investments provide reliable returns.
固定収入の投資は信頼性の高いリターンを提供します。
B2 verb /fʊlˈfɪl/

fulfill

実現する
Meaning
to complete or accomplish something, especially a task or promise
Example
He worked hard to fulfill his dreams.
彼は夢を実現するために一生懸命働きました。
C1 noun /fɑːrs/

farce

茶番
Meaning
a comic dramatic work using buffoonery and horseplay, or a ridiculous situation
Example
The meeting turned into a complete farce with everyone arguing.
会議は完全に茶番に変わり、みんなが議論していた。
C2 noun /fækˈsɪmɪli/

facsimile

コピー
Meaning
an exact copy or reproduction of a document
Example
He sent a facsimile of the contract to the client.
彼は契約書のコピーをクライアントに送った。
C2 noun /ˈfɛndər/

fender

フェンダー
Meaning
a part of a vehicle that frames a wheel well to protect against mud or debris
Example
The car's fender was dented in the accident.
車のフェンダーは事故でへこんでしまいました。
B2 adjective /ˈfruːt.fəl/

Fruitful

実り多い; 有益な; 成功した;
Meaning
productive; beneficial; successful;
Example
Our discussion was very fruitful and led to many new ideas.
私たちの議論は非常に実り多く、新しいアイデアをたくさん生み出しました。
C1 noun /ˈfæk.ʃən/

Faction

派閥
Meaning
a small organized dissenting group within a larger one
Example
Different factions within the party disagreed about the new policy.
党内の異なる派閥は新しい政策に対して意見が一致しませんでした。
C2 adjective/noun /fɪˈduː.ʃi.er.i/

fiduciary

信託の
Meaning
Involving trust, especially with regard to the relationship between a trustee and a beneficiary.
Example
Banks have fiduciary duties towards their clients.
銀行は顧客に対して信託義務を負っています。
C1 noun /ˈfɔːr.teɪ/ or /fɔːrt/

forte

得意
Meaning
a strong ability or talent; something one does particularly well
Example
Cooking is definitely her forte.
料理は間違いなく彼女の得意分野です。
A2 verb /fiːd/

feed

餌を与える
Meaning
to give food to a person or animal
Example
She feeds the birds every morning.
彼女は毎朝鳥に餌を与えます。
B2 noun /ˈfɜːrneɪs/

furnace

炉
Meaning
an enclosed structure in which heat is produced for a building or for melting metal
Example
The factory's furnace melted the metal quickly.
工場の炉は金属を迅速に溶かしました。
C1 verb /ˈflʌtər/

flutter

羽ばたく / 震える
Meaning
to move or flap quickly and lightly; to beat or wave with small rapid motions
Example
The butterfly began to flutter its wings in the sunlight.
蝶が日光の中で羽ばたき始めた。
A1 noun /fʌn/

fun

楽しみ
Meaning
enjoyment, amusement, or light-hearted pleasure
Example
We had a lot of fun at the party.
パーティーでとても楽しみました。
B1 verb /ˈfɛri/

ferry

フェリーで運ぶ
Meaning
to transport by boat; to carry back and forth
Example
The boat ferried passengers across the river.
船は乗客を川の向こうに運びました。
B1 noun /ˈfeɪ.vər/

Favour

好意; 手伝い; 親切
Meaning
approval, support, or liking for someone or something; a kind or helpful act
Example
Could you do me a favour and help me move this heavy box?
この重い箱を動かす手伝いをしてくれませんか？
A2 noun /ˈfiː.lɪŋ/

Feeling

感覚; 気持ち; 感情
Meaning
an emotional state or reaction; the capacity to experience physical sensations
Example
She had a strange feeling that something important was about to happen.
彼女は何か重要なことが起こる予感がした。
C2 adjective /fɪˈdjuːʃəl/

fiducial

信頼の、基準点として機能する
Meaning
based on trust or confidence; serving as a standard of reference
Example
The fiducial point on the map ensures accurate measurements.
地図上のフィデュシャルポイントは正確な測定を確保します。
B1 noun /ˈfʌndɪŋ/

funding

資金調達
Meaning
financial support for a project or organization
Example
The startup is seeking funding from investors.
スタートアップは投資家から資金調達を試みています。
A2 adverb /fɔːrˈɛvər/

forever

永遠
Meaning
For all future time; for always.
Example
She promised to love him forever.
彼女は永遠に彼を愛すると約束した。
C2 noun /ˈflɛdʒlɪŋ/

fledgeling

若鳥
Meaning
A young bird that has just developed its feathers and is learning to fly; a beginner.
Example
The fledgeling was trying hard to take its first flight.
若鳥は最初の飛行をしようとしていました。
C2 adjective /ˈfluːviəl/

fluvial

河川に関連する
Meaning
relating to or found in a river
Example
The fluvial deposits indicated the presence of an ancient river system.
河川堆積物は古代の川のシステムの存在を示していた。
C1 noun /ˈfɒdər/

fodder

飼料
Meaning
food for livestock such as cattle, horses, or sheep; also something considered of little value but used to supply a demand
Example
The farmer stored enough fodder for the cattle to last through winter.
農家は家畜が冬を越せるように十分な飼料を貯めておいた。
C2 adjective /ˈfjuːzəbl/

fusible

融解可能な
Meaning
Capable of being melted or fused.
Example
The engineer used a fusible alloy in the experiment.
エンジニアは実験で融解可能な合金を使用しました。
C1 adjective ˈfjuː.taɪl

futile

無駄な
Meaning
Incapable of producing any useful result; pointless.
Example
His attempts to change the situation were futile.
状況を変えるための彼の試みは無駄だった。
B1 noun /ˈfes.tə.vəl/

Festival

フェスティバル; 祭り;
Meaning
a day or period of celebration, typically for religious reasons; an organized series of concerts, films, etc.
Example
The music festival attracted thousands of visitors from around the world.
音楽フェスティバルは世界中から何千人もの観客を魅了しました。
A2 adjective /ˈfroʊzən/

frozen

凍った
Meaning
preserved by being made extremely cold; turned into ice
Example
The lake was completely frozen during winter.
湖は冬に完全に凍っていた。
B2 noun/verb /flɑːk/

flock

群れ
Meaning
a group of birds or animals; to gather or move in a crowd
Example
Tourists flocked to the beach during summer.
観光客は夏にビーチに集まりました。
C1 verb /ˈfɪdʒɪt/

fidget

そわそわする、落ち着かない
Meaning
to make small movements, especially because of nervousness or impatience
Example
The child began to fidget during the long lecture.
子供は長い講義中に落ち着かなくなり始めました。
C1 noun /ˈfɔːrwɜːrd/

foreword

序文
Meaning
a short introduction at the beginning of a book, typically written by someone other than the author
Example
The foreword of the book was written by a famous historian.
その本の序文は、有名な歴史家によって書かれました。
B2 noun /ˈfjʊr.i/

Fury

激しい怒りや暴力的な感情;
Meaning
wild or violent anger; extreme intensity of emotion or activity
Example
His fury was evident when he discovered someone had stolen his bicycle.
彼の怒りは彼が自転車を盗まれたことに気づいたときに明らかだった。
C1 adjective /ˈfruː.ɡəl/

Frugal

節約的; 倹約的
Meaning
economical; thrifty;
Example
She is very frugal and saves money by buying only necessary items.
彼女はとても倹約的で、必要な物だけを買ってお金を節約しています。
B2 verb /ˈfrʌsˌtreɪt/

frustrate

フラストレートする
Meaning
to prevent from accomplishing; to make someone feel annoyed
Example
The traffic jam frustrated all the commuters.
渋滞はすべての通勤者をフラストレートさせました。
A2 adverb/adjective/verb /ˈfɜːrðər/

further

進める
Meaning
At a greater distance; to advance or promote something.
Example
She studied hard to further her career.
彼女はキャリアを進めるために一生懸命勉強した。
C2 noun /ˈflætʃələns/

flatulence

消化器系のガスの蓄積
Meaning
the accumulation of gas in the digestive system; excessive gas in the stomach or intestines
Example
Eating beans can sometimes cause flatulence.
豆を食べると時々おならが出ることがあります。
B1 noun /foʊk/

folk

人々
Meaning
people in general, often referring to a group or community
Example
Country folk often live a simple life.
田舎の人々はよくシンプルな生活をしています。
B2 noun /ˈfrɪkʃən/

friction

摩擦
Meaning
the resistance that one surface or object encounters when moving over another; conflict or tension between people or groups
Example
There was friction between the two departments over resource allocation.
リソース配分に関して、二つの部門間に摩擦がありました。
B2 noun /ˈfɪlmˌmeɪkər/

filmmaker

映画製作者
Meaning
a person who makes films, typically as a profession
Example
He is a well-known filmmaker in the industry.
彼は業界で有名なフィルムメーカーです。
C2 noun /fiːf/

fief

封建制度の下で保有される土地; 支配領域または制御区域
Meaning
an estate of land held under the feudal system; a domain or area of control
Example
The knight was granted a fief by the lord for his service.
騎士はそのサービスに対して領主から封土を与えられました。
C1 verb /fret/

fret

心配する
Meaning
to worry or be anxious; to be troubled
Example
Don't fret about the exam results.
試験結果について心配しないでください。
C2 adverb /ˈfɔːrbi/

forby

その上
Meaning
In addition; besides (archaic Scottish/English word).
Example
He is kind and generous, and wise forby.
彼は親切で寛大で、さらに賢いです。
A1 verb /fərˈɡet/

forget

忘れる
Meaning
to be unable to remember something; to fail to bring something to mind
Example
Don't forget to lock the door when you leave.
出かけるときはドアを閉め忘れないでください。
C1 adjective /ˈfɜːr.vənt/

fervent

情熱的な、熱心な
Meaning
having or showing intense passion or enthusiasm
Example
She gave a fervent speech about climate change.
彼女は気候変動について情熱的なスピーチを行った。
C2 adjective /ˈflæb.i/

Flabby

柔らかくてだらしない; しっかり感や筋肉の張りがない; 弱い
Meaning
soft and loose; lacking firmness or muscle tone; weak
Example
His flabby arms showed he needed to exercise more.
彼のだらしない腕は、もっと運動する必要があることを示していました。
C1 noun /ˈfɔːrˌbɛərz/

forebears

先祖
Meaning
Ancestors or people in previous generations from whom one is descended.
Example
We must honor the traditions of our forebears.
私たちは先祖の伝統を尊重しなければなりません。
B1 adjective /fɪkst/

fixed

固定された, 安定した
Meaning
firmly in place; not changing or movable
Example
The schedule for the meeting is fixed for Monday morning.
会議のスケジュールは月曜日の朝に固定されています。
C1 noun /fɪˈdɛl.ɪ.ti/

fidelity

忠誠心
Meaning
Faithfulness to a person, cause, or belief, demonstrated by continuing loyalty and support.
Example
A dog's fidelity to its owner is unmatched.
犬の忠誠心はその飼い主に対して比類のないものです。
B1 adjective /ˈfɔːrmər/

former

元
Meaning
Having been previously in a particular role or position.
Example
He is a former president of the association.
彼はその協会の元会長です。
B2 adjective /ˈflɔːrəl/

floral

花のような
Meaning
Relating to flowers or decorated with flowers.
Example
She wore a beautiful floral dress to the party.
彼女はパーティーに美しい花のようなドレスを着ていった。
C1 verb/noun ˈfæð.əm

fathom

理解する
Meaning
To understand after much thought; to measure the depth of water; to comprehend.
Example
It is difficult to fathom the depths of the ocean.
海の深さを理解するのは難しい。
C1 noun, verb /fɔːrd/

ford

浅瀬
Meaning
A shallow place in a river where one can cross; to cross a river at such a place.
Example
The travelers decided to ford the river at dawn.
旅行者たちは夜明けに川を渡ることに決めました。
B2 noun/adjective /ˈfluːɪd/

fluid

流体
Meaning
a substance that can flow easily, such as liquid or gas; smooth and adaptable
Example
The artist's fluid movements impressed the audience.
アーティストの流れるような動きは観客を感動させました。
B1 adverb /ˈfriːli/

Freely

自由に; 制限なく;
Meaning
without restriction; openly; willingly
Example
She spoke freely about her experiences during the interview.
インタビュー中に彼女は自由に自分の経験について話した。
C1 noun (plural of fungus) /ˈfʌndʒaɪ/

fungi

菌類
Meaning
a group of spore-producing organisms such as mushrooms, molds, and yeasts
Example
Fungi play an important role in breaking down organic matter in nature.
菌類は自然界で有機物を分解する重要な役割を果たします。
B2 noun /flɛkˈsɪbɪləti/

flexibility

柔軟性
Meaning
The quality of bending easily without breaking; willingness to change or compromise.
Example
The flexibility of the working hours made it easier to balance work and personal life.
労働時間のフレキシビリティにより、仕事とプライベート生活のバランスが取りやすくなった。
C1 noun /ˈfɔːrɡraʊnd/

foreground

前景
Meaning
the part of a scene that is nearest to and in front of the viewer
Example
The flowers in the foreground brightened the picture.
前景にある花が絵を明るくしました。
B2 adjective /ˌfjuːtʃəˈrɪstɪk/

futuristic

未来的な
Meaning
Having or involving very modern technology or design that is advanced beyond what is currently available
Example
Futuristic technologies are transforming industries worldwide.
未来的な技術は、世界中の産業を変革しています。
A2 adjective /fɪt/

Fit

適切な; 健康な; 良い体調の; 準備ができている
Meaning
suitable; appropriate; healthy; in good physical condition; ready
Example
He is fit and healthy.
彼はフィットで健康です。
A1 noun /ˈfraɪ.deɪ/

friday

金曜日
Meaning
the day of the week following Thursday and preceding Saturday
Example
We have a team meeting every Friday afternoon.
私たちは毎週金曜日の午後にチーム会議があります。
B2 adverb /ˈfɔ:rmoast/

Foremost

最も重要なこと; 何よりもまず
Meaning
most importantly; above all; in the first place
Example
First and foremost, we need to ensure safety.
まず第一に、安全を確保する必要があります。
B2 noun /ˈfeɪbəl/

fable

寓話
Meaning
a short story, typically featuring animals as characters, that conveys a moral lesson
Example
Aesop’s fables are famous for teaching valuable lessons through simple stories.
イソップの寓話は、簡単な物語を通して貴重な教訓を教えることで有名です。
C1 noun /flʌks/

flux

フロー
Meaning
continuous change or movement; the rate of flow of something
Example
The company was in a state of constant flux during the reorganization.
会社は再編成の間、絶え間ない変化の中にありました。
C2 adjective /ˈfɔːnɪŋ/

fawning

過度のほめ言葉
Meaning
displaying exaggerated flattery or affection
Example
Her fawning compliments made everyone uncomfortable.
彼女の過度のほめ言葉は、皆を不快にさせました。
C2 noun /flæks/

flax

フラックス
Meaning
a plant whose fibers are used to make linen and whose seeds are edible
Example
Flax is often used in making linen fabrics.
フラックスは、リネン生地を作るために頻繁に使用されます。
B2 noun /frɔːd/

Fraud

詐欺
Meaning
wrongful or criminal deception intended to result in financial or personal gain
Example
The company was investigated for credit card fraud and money laundering.
その会社はクレジットカード詐欺とマネーロンダリングで調査されました。
C1 adjective /fɪkˈtɪʃəs/

fictitious

虚構の、偽の
Meaning
not real or true; imaginary or fabricated
Example
The story he told was entirely fictitious.
彼が話した話は完全に虚構だった。
C2 adjective /ˈfæləbl/

fallible

誤りを犯しやすい
Meaning
capable of making mistakes or being wrong
Example
Even experts are fallible and can make errors.
専門家でさえ、誤りを犯し、エラーをすることがあります。
B1 noun freɪm

Frame

額縁
Meaning
A rigid structure that surrounds something such as a picture, door, or windowpane.
Example
A framed family tree can be displayed in your home.
額縁に入れた家系図は家で展示できます。
A1 noun/verb /fɪlm/

film

映画
Meaning
a motion picture or movie; or to record on camera
Example
They watched a film together on the weekend.
彼らは週末に一緒に映画を見ました。
C1 noun /fɪˈnɑːleɪ/

finale

フィナーレ
Meaning
the last part or conclusion of a performance, event, or series
Example
The concert ended with a spectacular finale.
コンサートは壮観なフィナーレで終わりました。
A2 noun /frʌnt/

front

前面
Meaning
the forward-facing part of something
Example
The house has a garden in front.
家の前に庭があります。
B2 adverb /ˈfɔːrməli/

formally

正式に
Meaning
in a formal or official manner; according to established rules or conventions
Example
The agreement was formally signed by both parties.
その合意は両当事者によって正式に署名された。
C2 adjective /ˈfɜːr.vɪd/

Fervid

情熱的な; 非常に熱心な; 感情で燃えている
Meaning
passionate; intensely enthusiastic; burning with emotion
Example
She gave a fervid speech about environmental protection.
彼女は環境保護についての熱烈なスピーチをしました。
B1 noun /ˈfʌŋkʃən/

function

機能
Meaning
An activity or purpose natural to or intended for a person or thing.
Example
The main function of the heart is to pump blood.
心臓の主な機能は血液をポンプすることです。
C1 noun/verb ˈfɒr.ɪdʒ

forage

飼料、食べ物を探す
Meaning
Food for horses and cattle, especially dried hay or feed; to search for food.
Example
Animals forage for food during the winter months.
動物たちは冬の間に食べ物を探します。
C2 adjective /ˈfʊtˌluːs/

footloose

自由な
Meaning
Free to go anywhere or do anything; not tied down by responsibilities.
Example
After graduating, he felt footloose and ready to explore the world.
卒業後、彼は自由を感じ、世界を探索する準備ができていました。
C2 noun /ˈflæɡ ˌɒfɪsər/

flag-officer

旗艦司令官
Meaning
a senior naval officer entitled to fly a flag to mark the command
Example
The flag-officer reviewed the fleet before the ceremony.
旗艦司令官は儀式の前に艦隊を視察しました。
C1 verb /ˈfɜːr.tɪ.laɪz/

fertilize

肥料を施す
Meaning
to make soil or land more fertile by adding substances
Example
Farmers fertilize the fields to increase crop yield.
農家は作物の収穫量を増やすために畑に肥料を施す。
C2 adjective /ˈfɛtɪd/

fetid

悪臭のある、臭い
Meaning
having a strong, unpleasant smell
Example
The fetid smell from the garbage was unbearable.
ゴミからの臭いは耐えられなかった。
C2 noun /ˈfɒpəri/

foppery

虚飾
Meaning
Foolish or excessive concern with one's appearance or manners; pretentious behavior.
Example
His obsession with fashion was dismissed as mere foppery.
彼のファッションへの執着は単なる虚飾と見なされた。
B2 adverb /ˌfʌndəˈmɛntəli/

fundamentally

基本的に
Meaning
in a basic and important way; at the core
Example
The two theories are fundamentally different.
この二つの理論は基本的に異なります。
C2 adjective /ˈfraʊzi/

frowzy

だらしない
Meaning
Unkempt, messy, or having a musty, unpleasant smell.
Example
He entered the room with a frowzy appearance after sleeping on the couch.
彼はソファで寝た後、だらしない外見で部屋に入ってきました。
B2 noun ˈfeɪs tə ˈfeɪs ˈbætl

face-to-face battle

面と面の戦い
Meaning
A direct confrontation or fight between opposing forces.
Example
The warriors fought a face-to-face battle with the enemies.
戦士たちは敵と面と面で戦った。
C1 noun /fiˈæs.koʊ/

fiasco

完全な失敗
Meaning
a complete failure, especially a ludicrous or humiliating one
Example
The event turned into a complete fiasco due to poor planning.
計画の悪さからそのイベントは完全な失敗に終わった。
B2 noun ˈfrʌn.tɪərz

frontiers

最前線
Meaning
The extreme limit of settled land beyond which lies wilderness; the limits of knowledge or achievement in a particular field.
Example
The project pushes the frontiers of space exploration.
このプロジェクトは宇宙探査の最前線を押し広げています。
C2 adjective /ˈfædɪʃ/

faddish

一時的な流行
Meaning
Following a temporary trend or fashion
Example
Wearing neon clothes was a faddish style in the 1980s.
ネオンの服を着ることは1980年代の流行だった。
C1 noun /fɔːrˈmæl.ə.ti/

Formality

形式
Meaning
the rigid observance of rules of convention or etiquette; a thing done simply to comply with requirements
Example
The signing of the contract was just a formality; the deal was already agreed upon.
契約書にサインすることは単なる形式でした。契約はすでに合意されていました。
C2 verb /ˈfrɪtər/

fritter

浪費する
Meaning
To waste time, money, or energy on trivial matters.
Example
He frittered away his savings on unnecessary gadgets.
彼は無駄にお金を浪費しました。
A2 noun ˈfɔːrɪsts

Forests

森
Meaning
Large areas covered with trees and undergrowth, providing natural habitats for wildlife.
Example
Forests provide shelter and food for butterflies.
森は蝶々にとって避難所と食料を提供します。
C2 noun /ˈfɜːrnəri/

fernery

シダ植物の栽培所、シダを育てる場所
Meaning
a place or greenhouse where ferns are cultivated
Example
The garden's fernery was full of exotic plants.
庭のファーネリーは珍しい植物でいっぱいだった。
C1 verb /ˈfɔːrfɪt/

forfeit

Meaning
to lose or give up something, usually as a penalty for wrongdoing
Example
He had to forfeit the match after breaking the rules.
C1 adjective /freɪl/

frail

脆弱
Meaning
Physically weak and delicate.
Example
The old man was too frail to walk without help.
その高齢者は助けなしでは歩けないほど脆弱だった。
C2 noun /ˈfrækɑː/

fracas

騒動
Meaning
A noisy disturbance or quarrel.
Example
The fracas outside the bar drew the attention of the police.
バーの外での騒動が警察の注意を引きました。
C2 verb /flɛdʒ/

fledge

飛べるようになる
Meaning
To develop wing feathers large enough for flight; to bring up until able to fly.
Example
The young birds will fledge in a few weeks.
若い鳥たちは数週間以内に飛べるようになる。
C1 noun /ˈfɔːrˌrʌnər/

forerunner

先駆者
Meaning
A person or thing that comes before another; a predecessor or harbinger.
Example
The Wright brothers were the forerunners of modern aviation.
ライト兄弟は現代の航空の先駆者でした。
A2 number /ˈfɪfti/

fifty

五十
Meaning
the number 50
Example
The stadium can hold fifty thousand people.
スタジアムは五万人を収容できます。
A2 adjective /ˈfraɪtənd/

frightened

怯えた
Meaning
feeling fear or anxiety; scared
Example
The child was frightened by the loud noise.
その子供は大きな音に怯えた。
B2 noun /ˈfræk.ʃən/

Fraction

分数; 部分
Meaning
a numerical quantity that is not a whole number; a small or tiny part of something
Example
Only a small fraction of the population voted in the local election.
地方選挙で投票したのは人口のごく一部に過ぎなかった。
C1 noun /ˈfaɪər.wɔːl/

firewall

ファイアウォール
Meaning
A network security system that monitors and controls incoming and outgoing network traffic based on predetermined security rules.
Example
A firewall protects networks from cyber-attacks.
ファイアウォールはネットワークをサイバー攻撃から守ります。
A2 noun /ˈfɔːrɪst/

Forest

森
Meaning
a large area covered chiefly with trees and undergrowth
Example
We went hiking in the dense forest yesterday.
昨日、私たちは密林をハイキングしました。
C2 adjective /ˈflʌməksd/

flummoxed

困惑した
Meaning
Completely confused or bewildered.
Example
He looked flummoxed after hearing the strange question.
彼はその奇妙な質問を聞いた後、困惑しているように見えた。
A2 adjective /ˈfæstɪst/

fastest

最速の
Meaning
moving or capable of moving at the highest speed
Example
Usain Bolt is the fastest runner in the world.
ウサイン・ボルトは世界で最も速いランナーです。
B2 noun /fliːt/

fleet

艦隊
Meaning
a group of ships, vehicles, or aircraft operating together under one command
Example
The navy deployed its entire fleet for the exercise.
海軍は演習のためにその全艦隊を展開した。
C1 adjective /ˈfiːbl/

feeble

弱い, 無力
Meaning
lacking physical strength or vigor; weak
Example
After the illness, she felt too feeble to stand.
病気の後、彼女は立ち上がるにはあまりにも弱かった。
C1 noun /fruˈɪʃən/

fruition

実現
Meaning
The realization or fulfillment of a plan, project, or desire.
Example
Her dream of becoming a doctor finally came to fruition.
医者になるという彼女の夢はついに実現した。
A2 noun, verb /fuːl/

fool

バカ
Meaning
a silly or stupid person; to trick someone
Example
He felt like a fool after believing the prank.
いたずらを信じた後、彼は自分がバカだと思った。
C1 verb ˈflʌk.tʃu.eɪt

fluctuate

変動する
Meaning
To regularly increase or decrease.
Example
Stock prices fluctuate due to market conditions.
株価は市場の状況によって変動します。
B2 noun /fʌs/

Fuss

騒ぎ; 無駄な心配
Meaning
unnecessary worry or bother about something; agitated excitement over a trivial matter
Example
She made such a fuss about the small stain on her dress that everyone noticed.
彼女はドレスの小さなシミについてそんなに騒いだので、みんなが気づきました。