Uni-tasker

An object with one function, ideally, designed to be extremely good at what it does. A waffle iron, for example, can only be used to make waffles, but it tends to make waffles extremely effectively, justifying its existence as a uni-tasker. Objects as varied as saddles to soap dishes or rice cookers can be considered uni-taskers.

The only uni-tasker allowed in your kitchen is a fire extinguisher.