Lewis & Short

ustŭlo, āvi, ātum, 1, v. a. [uro].

  1. I. Lit.
    1. A. In gen., to burn a little, to scorch, singe (very rare; syn. amburo): palos, Vitr. 5, 12: taleas oleagineas, id. 1, 5: caput ferventi ferro, i. e. to crisp the hair, Auct. Priap. 46.
    2. * B. Pregn., to burn up, consume by fire: scripta lignis, Cat. 36, 8.
  2. * II. Transf., to pinch, nip, or blast with cold: gemmas (arboris) frigoris aurā, Auct. Priap. 62.