/ Dictionary / Index S sei: Meaning and Definition of Find definitions for: sei Pronunciation: (sā), [key] — n. See Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. Sehna knot seicento 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