Definition from Wiktionary, the free dictionary
Alternative forms 
- inpossible (obsolete)
- Not possible, not able to be done.
- Nothing is impossible, only impassible. — Lewis Carroll, Alice in Wonderland
- It is difficult, if not impossible, to memorise 20,000 consecutive numbers.
- (colloquial, of a person) Very difficult to deal with.
- You never listen to a word I say – you're impossible!
- unpossible (rare)
Derived terms 
very difficult to deal with
impossible (plural impossibles)
- an impossibility
- Late 14th century: “Madame,” quod he, “this were an impossible!” — Geoffrey Chaucer, ‘The Franklin's Tale’, Canterbury Tales
- (uncountable) (with definite article) that which seems impossible
- If we work together, we can achieve the impossible!
impossible m, f (masculine and feminine plural impossibles)
impossible (masculine and feminine, plural impossibles)
Middle French 
impossible m and f (plural impossibles)