General:
* Unresponsiveness
* Insensibility
* Stupor
* Coma (in cases of deep unconsciousness)
* Sleep (in the case of natural unconsciousness)
* Blackout (in the case of temporary unconsciousness)
* Fainting (in the case of brief unconsciousness)
* Transe (in the case of an altered state of consciousness)
More specific:
* Hypnosis (induced state of unconsciousness)
* Anesthesia (induced state of unconsciousness for medical procedures)
* Narcosis (state of unconsciousness induced by drugs)
The best word to use will depend on the specific situation and the level of unconsciousness you want to convey.