early 14c. "relative freedom of a noble metal from alloy or other impurities," from Anglo-French alai, Old French aloi, from aloiier (see alloy (v.)). Meaning " base metal alloyed with a noble metal" is from c.1400. Modern spelling from late 17c.
alloy al·loy (āl'oi', ə-loi')
A homogeneous mixture or solid solution of two or more metals, the atoms of one replacing or occupying interstitial positions between the atoms of the other.
A material made of two or more metals, or of a metal and another material. For example, brass is an alloy of copper and zinc; steel is an alloy of iron and carbon. Alloys often have unexpected characteristics. In the examples given above, brass is stronger than either copper or zinc, and steel is stronger than either iron or carbon.