Mortal  —adj. 1 subject to death. 2 causing death; fatal. 3 (of combat) fought to the death. 4 associated with death (mortal agony). 5 (of an enemy) implacable. 6 (of pain, fear, an affront, etc.) Intense, very serious. 7 colloq. Long and tedious (for two mortal hours). 8 colloq. Conceivable, imaginable (every mortal thing; of no mortal use). —n. Human being.  mortally adv. [latin mors mort- death]