n.

1. 自我；自我意识[C][U]
   He has an enormous ego.

   他具有强烈的自我意识。

2. 自尊心；自负[U]
   That failure was a blow to my ego.

   那项失败是对我自尊心的一个打击。

n.

1. a person's sense of self-esteem or self-importance.
2. Psychoanalysis  the part of the mind that mediates between the conscious and the unconscious and is responsible for reality testing and a sense of personal identity. Compare with id and superego.
3. Philosophy  (in metaphysics) a conscious thinking subject.