yay-say Share definition Flag noun. A yay-say is someone who praises, or gives a positive opinion, to something, usually a film. the opposite is nay-say Are you a yay-say of The Matrix? -err, no I dont like it -so your a nay-say yay-say by wonderfool April 2, 2004 0 0 Get merch Get the yay-say mug. Buy Now — $32.95 See more merch