IPA: /ʌnˈkɒnʃəsnəs/
KK: /ʌnˈkɒnʃəsnəs/
The condition of not being aware of one's surroundings or thoughts, often due to a lack of consciousness.
After the accident, he fell into a state of unconsciousness for several hours.
Unconsciousness → It is formed from "un-" (meaning not), "conscious" (from Latin "conscientem", meaning aware or knowing), and "-ness" (meaning the state of). The word "unconsciousness" refers to the state of not being aware or not knowing.
Think of 'not' ('un-') being added to 'aware' ('conscious') to remember that 'unconsciousness' means the state of not being aware.