One of two or more words pronounced and/or spelled alike but different in meaning.
Example:
The pool of "a pool of water" and the pool of "a game of pool" are homonyms.
Homonym is a troublesome word because it can refer to three distinct classes of words. Homonyms can be words that merely sound alike -- such as to, too, and two -- but are different in spelling and meaning. Homonyms can also be words that are spelled alike -- such as bow (of a ship) and bow (and arrow) -- but are different in pronunciation and meaning. Finally, homonyms can be words with identical spellings and pronunciations but different meanings -- such as quail (the bird) and quail (to cringe). Some writers and speakers prefer to limit homonym to this last sense.