alter ego n[Latin, literally, second I]
: second self
: a person or entity vicariously liable for another (as an agent) [had the officer been the alter ego of the corporation "J. J. White and R. S. Summers"] compare instrumentality NOTE: The concept of a legal alter ego is used primarily to hold the controlling parties of a corporation personally liable instead of limiting liability to the corporate entity.
Source: Merriam-Webster's Dictionary of Law ©1996. Merriam-Webster, Incorporated. Published under license with Merriam-Webster, Incorporated.