Entry 1 sense Webster, 1913 Coarsen /(kōrs"'n)/ · Coars·en · IPA /ˈkɔː(ɹ)sən/ 01 v. t. To make coarse or vulgar; as, to coarsen one's character. 1. To make coarse or vulgar; as, to coarsen one's character.[R.]