It means going in and out of consciousness or awareness.
Humans lose consciousness when the oxygen supply to the brain gets low.
Consciousness though a real phenomenon little is knows about its physical particulars. It seems to be related to the complexity of brain actions. It also seems to require a biological brain to have consciousness and thereby it has mass and energy. "Pure consciousness" is a science fiction concept implying awareness without physical structure. As far as it is understood such a phenomenon is not possible.
The cerebrum
cerebrum
natural progression ; harmony
Stream of Consciousness
Has he gained consciousness yet?
Consciousness
Since there is broadly a lack of necessity for the plural form of consciousness, there isn't necessarily a cataloged form of it. Because of this, forms of a pluralized consciousness are often denoted in terms such as a "hive mind" or "collective consciousness".
Consciousness resides in the cerebral cortex.
Consciousness - album - was created in 2008.
Universal Consciousness was created in 1972.
Anthropology of Consciousness was created in 1990.
Thinking about Consciousness was created in 2002.
Consciousness Explained was created in 1991.
A Universe of Consciousness was created in 2000.