/ Dictionary / Index S seisin: Meaning and Definition of Find definitions for: sei•sin Pronunciation: (sē'zin), [key] — n. Law. seizin. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. seise seising Related Content Daily Word Quiz: paradox Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language