the last or most difficult challenge or area of exploration
le dernier ou le plus difficile défi ou domaine d'exploration (le dernier ou le plus difficile defi ou domaine d'exploration)
"For many scientists, space remains the final frontier."
"Pour de nombreux scientifiques, l'espace reste la dernière frontière." (Pour de nombreux scientifiques, l'espace reste **la derniere frontiere**.)
to waste more money on something that has already failed
to become crazy or mentally unstable
To investigate more thoroughly or find out more details.
to change the rules or conditions to make success harder
to hide or suppress your emotions
to exaggerate or make something seem more important than it...