/ Dictionary / Index L lactobacillus: Meaning and Definition of Find definitions for: lac•to•ba•cil•lus Pronunciation: (lak"tō-bu-sil'us), [key] — pl. -cil•li any long, slender, rod-shaped, anaerobic bacterium of the genus Lactobacillus, that produces large amounts of lactic acid in the fermentation of carbohydrates, esp. in milk. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: lactobacillus (Thesaurus) lacto- lactoferrin Related Content Daily Word Quiz: rustic Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language