/ Dictionary / Index U undersea: Meaning and Definition of Find definitions for: un•der•sea Pronunciation: (un'dur-sē"), [key] — adj. located, carried on, or used under the surface of the sea: undersea life. —adv. underseas. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: undersea (Thesaurus) underscore underseas Related Content Daily Word Quiz: fidelity Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language