Psyche

(noun) that which is responsible for one's thoughts and feelings; the seat of the faculty of reason. Synonyms: mind, head, brain, psyche, nous. Examples: "His mind wandered." "I couldn't get his words out of my head."

(noun) the immaterial part of a person; the actuating cause of an individual life. Synonyms: soul, psyche.

(noun) (Greek mythology) a beautiful princess loved by Cupid who visited her at night and told her she must not try to see him; became the personification of the soul.