To do something very well, particularly an examination (verb); first-rate (adjective), or an expert (noun).
Example:
1) I'm going to ace this exam - I've been studying all week!
2) Lois Lane was the ace reporter for The Daily Planet -- although she did have a lot of trouble uncovering Superman's identity!
Etymology:
In World War I, a pilot who shot down five enemy planes was called an 'ace', which is the powerful one card in a deck of playing cards. 'Ace' can be used as a verb (to do well) or as an adjective (excellent, best) or as a noun (a nickname for someone who is good at something, or for a good friend).
