Real Dictionary

alloy
variable noun: An alloy is a metal that is made by mixing two or more types of metal together.

alloy in American English
the relative purity of gold or silver; fineness
to make (a metal) less pure by mixing with a less valuable metal
noun: a substance composed of two or more metals, or of a metal or metals with a nonmetal, intimately mixed, as by fusion or electrodeposition
transitive verb: to mix (metals or metal with nonmetal) so as to form an alloy

alloy in British English
noun: a metallic material, such as steel, brass, or bronze, consisting of a mixture of two or more metals or of metallic elements with nonmetallic elements. Alloys often have physical properties markedly different from those of the pure metals
verb: to add (one metal or element to another metal or element) to obtain a substance with a desired property

alloy in Mechanical Engineering
noun: An alloy is a metal which is not pure because other elements have been added to it.