conscious
- consciousness - conscience - conscientious
‘conscious’
Conscious is an adjective. If you are conscious of something, you are aware of it.
She became conscious of Rudolph looking at her.
I was conscious that he had changed his tactics.
If you are conscious, you are awake, rather than asleep or unconscious.
The patient was fully conscious during the operation.
‘consciousness’
Consciousness is a noun. You can refer to your mind and thoughts as your consciousness.
Doubts were starting to enter into my consciousness.
If you lose consciousness, you become unconscious. If you regain consciousness or recover consciousness, you become conscious again after being unconscious. These are fairly formal expressions.
He fell down and lost consciousness.
He began to regain consciousness just as Kate was leaving.
She died in hospital without recovering consciousness.
In more informal English you can say that you pass out instead of ‘lose consciousness’, and come round instead of ‘regain/recover consciousness’.
He felt sick and dizzy, then passed out.
When I came round, I was on the kitchen floor.
‘conscience’
Conscience is a noun. Your conscience is the part of your mind that tells you whether what you are doing is right or wrong.
My conscience told me to vote against the others.
Their consciences were troubled by stories of famine and war.
‘conscientious’
Conscientious is an adjective. Someone who is conscientious is very careful to do their work properly.
We are generally very conscientious about our work.
She seemed a conscientious, serious young woman.