coarsen

verb2

1. •
   To make (more) coarse.

   • Because the wool is of poor quality, it will coarsen the fabric.
2. •
   To become (more) coarse.

   • He was intolerable now except under the influence of liquor, and as he seemed to decay and coarsen under her eyes, Gloria's soul and body shrank away from him […] — 1922