Source : Webster's Revised Unabridged Dictionary (1913)

Gay \Gay\, a. [Compar. {Gayer}; superl. {Gayest}.] [F. gai,
   perhaps fr. OHG. g?hi swift, rapid, G. g["a]h, j["a]h, steep,
   hasty; or cf. OHG. w?hi beatiful, good. Cf. {Jay}.]
   1. Excited with merriment; manifesting sportiveness or
      delight; inspiring delight; livery; merry.

            Belinda smiled, and all the world was gay. --Pope.

            Gay hope is theirs by fancy fed.      --Gray.

   2. Brilliant in colors; splendid; fine; richly dressed.

            Why is my neighbor's wife so gay?     --Chaucer.

            A bevy of fair women, richly gay In gems and wanton
            dress!                                --Milton.

   3. Loose; dissipated; lewd. [Colloq.]

   Syn: Merry; gleeful; blithe; airy; lively; sprightly,
        sportive; light-hearted; frolicsome; jolly; jovial;
        joyous; joyful; glad; showy; splendid; vivacious.