acerb, acerbic, acid, acrid, bitter, blistering, caustic, sulfurous, sulphurous, venomous, 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"

• unpleasant — not pleasant