To me, consciousness is when you are able to think and act on your own accord. Although I don't think it should be considered a binary 'you're either conscious or not' type of thing. For example, when I hit a certain weight squatting, I don't feel conscious at all. In fact, sometimes my vision will get dark and my mind blanks. I think certain stimuli can mess with your consciousness, and these stimuli have some way of changing how your brain operates to some capacity. Another example is when someone has had too much to drink. When you are nearly blackout drunk and have no recollection of what you have done, could you really consider that as being conscious?
Consciousness to me is an individual awareness of your unique thoughts, memories, feelings, situations and environments. I like the point you made about how you don't think a person who is blackout drunk should be considered conscious. I agree, because they have no individual awareness of their thoughts, memories, feelings, situations, or environment at that point in time when they are in that state.
I agree with both posts about the meaning of consciousness. It's a state where you are able to make decisions and act voluntarily. Therefore, a lack of consciousness means the person cannot think or act as they choose to do so, like someone who is blackout drunk.