/ Dictionary / Index B black dog: Meaning and Definition of Find definitions for: black' dog' Pronunciation: [key] — Informal. Informal. melancholy; despondency; the blues: The black dog is over him. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. black disease black duck Related Content Daily Word Quiz: resilient Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language