/ Dictionary / Index B black light: Meaning and Definition of Find definitions for: black' light' Pronunciation: [key] invisible infrared or ultraviolet light. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. black-letter day black-light trap Related Content Daily Word Quiz: careening Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language