From Middle English ye, ȝea, ya, ȝa, from Old English ġēa, iā (“yea, yes”), from Proto-Germanic *ja (“yes, thus, so”), from Proto-Indo-European *yē (“already”). Cognate with Scots yea, ya (“yes, yea, indeed, so”), Saterland Frisian ja, jee (“yes”), West Frisian ja (“yes”), Dutch ja (“yes”), German ja (“yes, yea”), Swedish ja, jo (“yes, well, indeed”), Icelandic já (“yes”), Latin iam (“now, already”), Italian già (“now, already”), Spanish ya (“now, already”).
yea (not comparable)
- (dated) Yes.
- Thus, so (now often accompanied by a hand gesture).
- (archaic) Or even, or more like, nay. Introduces a stronger and more appropriate expression than the preceding one.
- c. 1633, The Flea, by John Donne
- (in some dialects of American English, including Southern, Western, and African American Vernacular) Yeah, right, yes.
- Misspelling of yay.
- Misspelling of yeah. 
yea (plural yeas)
- An affirmative vote, usually but not always spoken