Definitions
1.nounAn affirmative vote, usually but not always spoken
2.adverbYes.
3.adverbThus, so (now often accompanied by a hand gesture)."The pony was yea high."
4.conjunctionOr even, or more like, nay. Introduces a stronger and more appropriate expression than the preceding one.
5.interjection(in some dialects of American English, including Southern, Western, and African American Vernacular) Yeah, right, yes.