microwave oven

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun An oven in which food is cooked, warmed, or thawed by the heat produced as microwaves cause water molecules in the foodstuff to vibrate.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun An oven that uses microwave energy to heat food or other items placed within it.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun kitchen appliance that cooks food by passing an electromagnetic wave through it; heat results from the absorption of energy by the water molecules in the food