/ Dictionary / Index S Sisinnius: Meaning and Definition of Find definitions for: Si•sin•ni•us Pronunciation: (si-sin'ē-us), [key] — n. popea.d.708. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. Sisera siskin Related Content Daily Word Quiz: spectral Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language