acerb, acerbic, acid, acrid, bitter, blistering, caustic, sulfurous, sulphurous, virulent, vitriolic -- (harsh or corrosive in tone; "an acerbic tone piercing otherwise flowery prose"; "a barrage of acid comments"; "her acrid remarks make her many enemies"; "bitter words"; "blistering criticism"; "caustic jokes about political assassination, talk-show hosts and medical ethics"; "a sulfurous denunciation"; "a vitriolic critique")
caustic, corrosive, erosive, vitriolic, mordant -- (of a substance, especially a strong acid; capable of destroying or eating away by chemical action)