noun

• (uncountable, psychology and philosophy, especially Kantianism) The mind's perception of itself as the subject or actor in its own states, unifying past and present experiences; self-consciousness, perception that reflects upon itself.
• (uncountable) Psychological or mental perception; recognition.
• (countable, psychology) The general process or a particular act of mental assimilation of new experience into the totality of one's past experience.