What is Alias?

Legal Definition
Practice. This word is prefixed to the name of a second writ of the same kind issued in the same cause; as, when a summons has been issued and it is returned by the sheriff, nil, and another is issued, this is called an alias summons. The term is used to all kinds of writs, as alias fi. fa., alias vend. exp. and the like. Alias dictus, otherwise called; a description of the defendant by an addition to his real name of that by wbich he is bound in the writing; or when a man is indicted and his name is uncertain, he may be indicted as A B, alias dictus C D. See 4 John. 1118; 1 John. Cas. 243; 2 Caines, R. 362; 3 Caines, R. 219.
-- Bouviers Law Dictionary
Legal Definition
Lat. Otherwise; at another time; in another manner; formerly.
See also
-- Black's Law Dictionary
Legal Definition
Otherwise; also known as; at another time.
-- Ballentine's Law Dictionary