Lewis & Short

prae-ūro, ussi, ustum, 3, v. a.,

  1. I. to burn before, burn at the end or point (class. but not in Cic.); esp. freq. in part. perf.: hasta praeusta, Liv. 1, 32: stipites ab summo praeacuti et praeusti, Caes. B. G. 7, 73, 6; cf.: multae praeustae sudes, id. ib. 5, 40: sudibus praeustis, Verg. A. 7, 524: praeusta et praeacuta materia, Caes. B. G. 7, 22 fin.: tela, hardened in the fire, Tac. A. 2, 14.
  2. II. In gen., to scorch, parch, wither: ne (uvae) praeurantur, Col. Arb. 11, 2 (dub.; al. perurantur).
    1. B. Also of cold: praeustis in transitu Alpium nive membris, frost-bitten, Plin. 3, 20, 24, § 134; cf. aduro.