Other forms: subconsciouses
Subconscious describes something that is just below your awareness, like at a subconscious level hoping your friend's boyfriend breaks up with her — you didn't even realize you felt that way until it happened.
If you are aware of something, you are conscious of it, like being conscious of your tendency to talk too much when you are nervous: you watch for it and try to control it. Most words that start with the prefix sub- are something “under” the root word: something subconscious is under or below your awareness. Maybe in time, it will surface — you might get to the root of why you get so nervous in the first place.