/ Dictionary / Index S semiarch: Meaning and Definition of Find definitions for: sem•i•arch Pronunciation: (sem'ē-ärch", sem'ī-), [key] — n. a half arch. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. semiaquatic semiarid Related Content Daily Word Quiz: fervor Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language