Most people know that microwave is short for microwave oven.
In English, we typically refer to things by the noun, not the adjective - for instance, we can call a green umbrella an umbrella, but not just 'a green'. Likewise, adjectives come before the noun in English.
I am pretty sure that microwave is the adjective and oven is the noun, since it is an oven that uses microwave radiation to cook food. Is there a particular reason we call 'microwave ovens' microwaves, or was that just to avoid confusion with a conventional oven?
I ask because I do a lot of work with radiation and wireless technologies, and I'm kind of annoyed that we use the same word for these "microwave ovens" as well as the actual type of electromagnetic wave that it uses.