Transformer

Etymology
From (something that transforms).

Noun

 * 1)  A toy in the  which has mechanical parts that allow it to be altered in appearance from its original form as a humanoid robot  to another form, usually a, depending on the toy.
 * 2)  In the  franchise, any of the alien humanoid robots that can mechanically alter their appearance, or "transform", into a vehicle, creature, or (rarely) a tool.