callousing,ppl.a.|ˈkæləsɪŋ| [f. callous a. or v. + -ing2.] That makes callous. 1921Sunday at Home Jan. 214/1 My fellow-citizens are engaged on labour which is hard and callousing.1928Sunday Express 8 Jan. 9/1 The hardships and callousing brutalities of a mercenary force.