/ Dictionary / Index U underseas: Meaning and Definition of Find definitions for: un•der•seas Pronunciation: (un"dur-sēz'), [key] — adv. beneath the surface of the sea. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. undersea undersecretariat 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