Source : Webster's Revised Unabridged Dictionary (1913)

Comatose \Co"ma*tose`\ (? or ?; 277), a. [From {Coma} lethargy.]
   Relating to, or resembling, coma; drowsy; lethargic; as,
   comatose sleep; comatose fever.

Source : WordNet®

comatose
     adj 1: relating to or associated with a coma; "comatose breathing";
            "comatose state"
     2: in a state of deep and usually prolonged unconsciousness;
        unable to respond to external stimuli; "a comatose
        patient"