1. Subject to death; destined to die; as, man is mortal. 2. Destructive to life; causing or occasioning death; terminating life; exposing to or deserving death; deadly; as, a mortal wound; a mortal sin. 3. Fatally vulnerable; vital. Last of all, against himself he turns his sword, but missing the mortal place, with his poniard finishes the work. Milton. 4. Of or pe...