/ Dictionary / Index S sial: Meaning and Definition of Find definitions for: si•al Pronunciation: (sī'al), [key] — n. Geol. the assemblage of rocks, rich in silica and alumina, that comprise the continental portions of the upper layer of the earth's crust. Cf.. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: sial (Thesaurus) Siad Barre sialadenitis Related Content Daily Word Quiz: quandary Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language