/ Dictionary / Index I interstitial: Meaning and Definition of Find definitions for: in•ter•sti•tial Pronunciation: (in"tur-stish'ul), [key] — adj. pertaining to, situated in, or forming interstices. situated between the cells of a structure or part: interstitial tissue. —n. an imperfection in a crystal caused by the presence of an extra atom in an otherwise complete lattice. Cf. vacancy (def. 6). Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: interstitial (Thesaurus) interstice interstitial-cell-stimulating hormone Related Content Daily Word Quiz: gregarious Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language