1. An internal knowledge or conviction that someone has of herself or himself: Ivan experienced a brief loss of consciousness when he slipped and fell down on the icy sidewalk:

Henry slowly regained consciousness after the surgery at the hospital.
2. The state or fact of being awake and able to understand what is happening around someone: The medication caused Sam to enter an altered state of consciousness.
3. The totality of the impressions, thoughts, and feelings, which make up what people are aware of: The political events produced by President Trump have become part of the national consciousness.