unconsciousness

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unconsciousness (un-kon-shŭs-nis) 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 or head injuries, or it may be brought about deliberately during general anaesthesia. See also coma.

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