Coma (noun)

1. A state of unconsciousness from which a person cannot be awakened, caused by injury, illness, or poison.
2. A profound state of unconsciousness caused by severe injury or illness.

Origin:

Late 16th century: from greek kōma "deep sleep".

Examples:

1. The patient has been in a coma for the past three weeks.
2. The doctors are not sure if he will ever regain consciousness from his coma.
3. The coma was caused by a severe head injury.
4. The patient was in a coma for several days but eventually recovered.
5. The coma was induced medically in order to allow the brain to rest and heal.