Pronunciation: (hā'dā"), [key]
1. the stage or period of greatest vigor, strength, success, etc.; prime: the heyday of the vaudeville stars.
2. Archaic.high spirits. Also,hey'dey.
Pronunciation: (hā'dā), [key]
(used as an exclamation of cheerfulness, surprise, wonder, etc.)
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.