(possibly obsolete) Happy, joyful, and lively.
The Gay Science
Quick, fast.
(possibly obsolete) Festive, bright, or colourful.
Pennsylvania Dutch include the plain folk and the gay folk.
Sexually promiscuous (of any gender), (sometimes particularly) engaged in prostitution.
Homosexual:
A pejorative:
(of a dog's tail) Upright or curved over the back.
(possibly obsolete) Considerable, great, large in number, size, or degree.
Somebody who is gay (in the sense of either homosexual or uncool).