Find the word you're looking for at wordreference.com. Make sure to choose English - French or French - English. Wordreference is a great way to find the right version of words. Use the example sentences to find one that matches you're meaning. For example, when you look up "cool", did you mean "a little cold" or "very good"?
Ma chambre est fraiche. - My room is chilly.
Ma chambre est cool. My room is excellent.