/ Dictionary / Index U understratum: Meaning and Definition of Find definitions for: un•der•stra•tum Pronunciation: (un'dur-strā"tum, -strat"um), [key] — pl. -stra•ta -strat•ums. a substratum. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. understrapper understrength Related Content Daily Word Quiz: spectral Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language