/ Dictionary / Index T treasonable: Meaning and Definition of Find definitions for: trea•son•a•ble Pronunciation: (trē'zu-nu-bul), [key] — adj. of the nature of treason. involving treason; traitorous. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: treasonable (Thesaurus) treason treasonous Related Content Daily Word Quiz: rustic Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language