Ego

·noun The conscious and permanent subject of all psychical experiences, whether held to be directly known or the product of reflective thought;

— opposed to non-ego.

ego
ĕgō̆ (ŏ always in poets of the best age, as Cat., Verg., Hor., etc.; ō ante-class. and post-Aug., ...

A New Latin Dictionary by Charlton T. Lewis Ph.D. and Charles Short, LL. D.
ego
ego (old and late, egō), gen.meī; dat.mihī, oftener mihi or mī; acc.and abl.mē; plur, nom., and acc...

An Elementary Latin Dictionary