Breadcrumb Home > Dictionary > Index N ninja: Meaning and Definition of Find definitions for: nin•ja Pronunciation: (nin'ju), [key] — pl. -ja, -jas. a member of a feudal Japanese society of mercenary agents, highly trained in martial arts and stealthwho were hired for covert purposes ranging from espionage to sabotage and assassination. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: ninja (Thesaurus) Ninigi ninjutsu ✖ Related Content Daily Word Quiz: spectral Analogy of the Day: Today’s Analogy Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language