/ Dictionary / Index S sigmatism: Meaning and Definition of Find definitions for: sig•ma•tism Pronunciation: (sig'mu-tiz"um), [key] — n. defective pronunciation of sibilant sounds. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. sigmate sigmoid Related Content Daily Word Quiz: stringent Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language