flagitious adj. + Add to list flagi·tious Literary SynonymsEtymology Synonyms atrociousgrievousheinousmonstrousOriginLATflāgitiōsus→OFRflagitieux→ENflagitious From Old French flagitieux or Latin flāgitiōsus, both ultimately from flāgitium (“shameful crime”), related to flagrum (“whip”).