Lewis & Short

insŏlesco, ĕre, v. inch. n. [insolens], to become unusual or strange.

  1. I. Lit., of the voice, to begin to change, to become manly: coepit Caelo vox insolescere, Tert. ad Nat. 2, 12; of the womb: uterus insolescens, i. e. swelling up, Hier. in Helv. 18.
  2. II. Trop., to grow haughty or insolent, to become elated (mostly post-Aug.): ad superbiam, Cato ap. Gell. 7, 3, 15: per licentiam animus humanus insolescit, Sall. C. 6, 7: rebus secundis, Tac. H. 2, 7; Just. 31, 8, 7.