/ Dictionary / Index U undersurface: Meaning and Definition of Find definitions for: un•der•sur•face Pronunciation: (un'dur-sûr"fis), [key] — n. underside; bottom surface. —adj. submerged; under the surface, as of water, earth, etc.: the undersurface speed of a submarine. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: undersurface (Thesaurus) understudy undertake 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