contraction of ne + est (third-person singular indicative present form of être)

except, if not

Used as an expression of affirmation after a statement, often translated into English as a tag question.

nobody's perfect

it's only fair! fair's fair!

except, except that; although; but

comparisons don't prove anything / one shouldn't compare things that aren't comparable; it's not the same

there's no such word as can't; nothing is impossible

nobody can be expected to achieve the impossible

Alternative spelling of à l'impossible nul n'est tenu