coars·en /ˈkorsṇ, ˈkɔr-/
  (vt.)(vi.)(使)變粗
  Coars·en v. t. To make coarse or vulgar; as, to coarsen one's character. [R.]
  ◄ ►
  coarsen
       v 1: make or become coarse or coarser; "coarsen the surface";
            "Their minds coarsened"
       2: make less subtle or refined; "coarsen one's ideals"