/ Dictionary / Index S spirillum: Meaning and Definition of Find definitions for: spi•ril•lum Pronunciation: (spī-ril'um), [key] — pl. -ril•la any of several spirally twisted, aerobic bacteria of the genus Spirillum, certain species of which are pathogenic for humans. See diag. under any of various similar microorganisms. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: spirillum (Thesaurus) Spires spirit Related Content Daily Word Quiz: endear Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language