IllinitionIl`li*ni"tion\, n. [L. illinire, illinere, to besmear; pref. il- in, on + linire, linere, to smear.]1. A smearing or rubbing in or on; also, that which is smeared or rubbed on, as ointment or liniment. 2. A thin crust of some extraneous substance formed on minerals. [R.] A thin crust or illinition of black manganese. --Kirwan.