assail v. + Add to list US //əˈseɪɫ// UK //ɐsˈeɪl// as·sail SynonymsAntonymsEtymology Synonyms assaultattackroundsnipe Antonyms defendOriginLATad→LA-LATassalio→OFRassalir→MEassailen→ENassail From Middle English assailen, from Old French assaillir, assalir, from Late Latin assalīre, from Latin ad (“at, towards”) + salīre (“jump”). See also assault.