Lewis & Short

ăcĭdus, a, um, adj. [aceo], sour, tart, acid.

  1. I. Lit.: sapor, Plin. 15, 27, 32, § 106; sorba, Verg. G. 3, 380: inula, Hor. S. 2, 2, 43: lac, Plin. 28, 9, 36, § 135: caseus, ib. 9, 34, § 132: acidissumum acetum, Plaut. Ps. 2, 4, 49.
    1. B. Transf.
      1. 1. Like acer, from taste to sound, harsh, rough, shrill: sonus acidior, Petr. 68; cf. canticum, ib. 31.
      2. 2. Acida creta, chalk steeped in vinegar, Mart. 6, 93.
  2. II. Fig., sharp, keen, pungent: homo acidae linguae, Sen. Contr. 5, 34; cf. Quint. 6, 3, 53: quod petis, id sane est invisum acidumque duobus, unpleasant, disagreeable, Hor. Ep. 2, 2, 64.
    Adv.: ăcĭde, bitterly, disagreeably: non acide feras, Vulg. Ecclus. 4, 9.
    Comp.: sibi acidius fuit, Petr. S. 92.