/ Dictionary / Index T tubercle bacillus: Meaning and Definition of Find definitions for: tu'bercle bacil"lus Pronunciation: [key] the bacterium, Mycobacterium tuberculosis, causing tuberculosis. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. tubercle tubercular Related Content Daily Word Quiz: portent Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language