An imprecise term for severely impaired awareness of self and the surrounding environment; most often used as a synonym for coma or unresponsiveness.
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n.
a condition of being unaware of one's surroundings, as in sleep, or of being unresponsive to stimulation. An unnatural state of unconsciousness may be caused by factors that produce reduced brain activity, such as lack of oxygen, head injuries, poisoning, blood loss, and many diseases, or it may be brought about deliberately during general anaesthesia. See also coma.
Medical dictionary. 2011.