Lewis & Short

ē-mātūresco, rŭi, 3, v. inch. n., to grow quite ripe, to come to maturity (very rare).

  1. I. In gen.: semen, Plin. 25, 4, 17, § 36: segetes, Gell. 2, 29, 7.
  2. * II. Trop., to grow softer, be mitigated: ira Caesaris, Ov. Tr. 2, 124.