pentad n. + Add to list pen·tad SynonymsEtymology Synonyms cinquefinfivefivesomephoebequintquintetquintupletOriginGRKπεντάς→ENpentad From Ancient Greek πεντάς (pentás), from πέντε (pénte, “five”) + -άς (-ás, “-ad”). By surface analysis, pent- + -ad.