/ Dictionary / Index A arsonist: Meaning and Definition of Find definitions for: ar•son•ist Pronunciation: (är'su-nist), [key] — n. a person who commits arson. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: arsonist (Thesaurus) arson arsphenamine Related Content Daily Word Quiz: penchant Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language