/ Dictionary / Index B birthday: Meaning and Definition of Find definitions for: birth•day Pronunciation: (bûrth'dā"), [key] — n. the anniversary of a birth. the day of a person's birth. a day marking or commemorating the origin, founding, or beginning of something. the festivities or celebration marking such a day or anniversary. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: birthday (Thesaurus) birth-control pill birthday suit Related Content Daily Word Quiz: neologism Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language