affordance

Many objects, such as tools and household appliances, are designed to afford us their proper use and constrain us from using them improperly. Affordance makes it easy to do the right thing, while constraints make it difficult to do the wrong thing. 
- Travis Lowdermilk. User-Centered Design. O’Reilly Media.

The term affordance refers to the perceived and actual properties that determine just how the thing could possibly be used. Affordances provide strong clues to the operations of things. For example, knobs are for turning. 
- Donald A. Norman. The Design of Everyday Things.

and wheels are for turning.