/ Dictionary / Index A argillaceous: Meaning and Definition of Find definitions for: ar•gil•la•ceous Pronunciation: (är"ju-lā'shus), [key] — adj. of the nature of or resembling clay; clayey. containing a considerable amount of clayey matter. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: argillaceous (Thesaurus) argil argillite Related Content Daily Word Quiz: resilient Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language