Donald Norman introduces the concept (originated by J. J. Gibson) of affordances, which he defines thus:
Affordances, then, are really literally all the possible actions that a person could perform on an object. You actually cannot see through wood, so it doesn't afford seeing through. "Affordances provide strong clues to the operations of things," he says, but he does not say the converse: just because a thing strongly suggests a certain action to the user, that doesn't make it an affordance.
Norman was annoyed enough by this misperception to attempt a correction:
It was probably already too late to change the common usage of the term. I know that I first encountered the term "affordance" being used to describe the little "grips" on the corner of a resizable window, which "afford" grabbing and dragging. Not a valid usage, in Norman's view.
There's not much chance of confusion, though. GUI designers cannot change any of the real affordances of the system, after all. And Norman's complaint seems to take things slightly too literally. It's true that it's merely a cultural convention that a beveled rectangle with some text inside represents a button, but granted we accept that metaphor, it doesn't seem much of a leap to say that the metaphorical button affords pushing in the same way that a physical button would. It's merely a question of whether we're thinking of the physical user in meatspace holding a mouse, or metaphorical user represented by the mouse pointer interacting "directly" with UI elements.
So, is Norman wrong to complain? No, but the takeaway isn't that we need to be more precise with our terms. It's this: we should remember that buttons and other such UI elements are merely cultural conventions, and not all users will interpret them the same way. What counts is what users actually perceive and do.