/ Dictionary / Index T transonic: Meaning and Definition of Find definitions for: tran•son•ic Pronunciation: (tran-son'ik), [key] — adj. Chiefly Aeron. close to the speed of propagation of sound; moving at 700–780 mph (1127–1255 km/h) at sea level. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: transonic (Thesaurus) transom window transonic barrier Related Content Daily Word Quiz: perspicacious Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language