(Alum) A metal which is used in cars because of its lightness. In pure form, it does not have the strength of the same size of iron. Thus car manufacturers use aluminum in an alloy form to produce body panels, wheels, engine blocks , transmission housings, differential housings , and even frames.
Meaning of ALUMINUM in English
English dictionary of automotive terms. Английский словарь автомобильных терминов. 2012