You searched for: “alter ego
alter ego
1. Another side of oneself; a second self; another aspect of one's self: "The characters Dr. Jekyll and Mr. Hyde were alter egos in a literary tale of horror."
2. An intimate friend or a constant companion; an inseparable friend.
3. A very close and trusted friend who seems almost a part of yourself.
4. A second self; a perfect substitute or deputy: "His assistant manager acts as his alter ego when he is not in the office."
This entry is located in the following units: alter- + (page 1) ego (page 1)
alter ego
The other "I" [ego].

An inseparable friend [your other self].

The idea is that an alter ego may be considered as speaking or acting for the other self within oneself.

This entry is located in the following unit: Latin Proverbs, Mottoes, Phrases, and Words: Group A (page 14)
Word Entries at Get Words: “alter ego
alter ego
1. Another self.
2. A very close friend.

"Dr. Jekyll and Mr. Hyde were alter egos in a tale of horror."

This entry is located in the following unit: allo-, alter- + (page 1)