(a.) Not perceiving, or not able to perceive.

a stranger to anesthetized asleep in Jesus at rest benumbed bereft of life blind to breathless called home callous carrion cataleptic catatonic caught napping cold comatose croaked dead dead and gone dead asleep dead to deadened deaf to death-struck deceased deep asleep defunct demised departed departed this life destitute of life done for doped dormant drugged dull exanimate fallen fast asleep finished flaked-out food for worms gone gone to glory gone west goofing off half-conscious idle impassible imperceptive impercipient in ignorance of inanimate incautious incognizant inert insensate insensible insensible to insensitive insentient late late lamented launched into eternity lifeless martyred mindless napping narcotized nirvanic no more nodding nonconceiving not with it numb numbed obdurate oblivious obtuse off-guard out out cold out of it passed on passive pushing up daisies quiet released reposing resting easy sainted semiconscious senseless sleeping sleepy slumbering smitten with death sound asleep spaced out still stillborn stoned strung out taken away taken off thick-skinned thick-witted unalert unanimated unaware unaware of uncautious unconscious unconscious of unfeeling unfelt unguarded unhearing uninsightful unknowing unmindful unmindful of unperceiving unperceptive unprehensive unprepared unready unrealizing unseeing unsuspecting unvigilant unwary unwatchful unwitting with the Lord with the saints without life without vital functions witless zonked zonked out