an aspect of an object which makes it obvious how the object is to be used
a property of an object, or a feature of the immediate environment, that indicates how that object or feature can be interfaced with
a property, or multiple properties, of an object that provides some indication of how to interact with that object or with a feature on that object
a relationship between an object in the world and the intentions, perceptions, and capabilities of a person
A relationship between an actor (i.e., person or animal) and an object; specifically, it refers to the possibility of the actor performing some action with the object, whether or not the actor can perceive that possibility. This term was introduced in J.J. Gibson's theory of ecological psychology, and later popularized (and misused) in Donald A. Norman's The Psychology of Everyday Things. See also: perceived affordance. Links: More on Affordances, Gibson's Definition of affordance.
Similar to Demand character: it's what you can do with a control. The affordance of a knob is to be turned ("Turn me"); a button is something you expect to press; and so on. Ever tried to click on something on a Web page that looks like a button, but isn't? That's an example of a poor affordance: a common finding in usability studies.
Critical clues about a device's proper operation as provided by the appearance of the device. Affordances specify the range of possible activities for interaction with a device. [Paraphrased from Don Norman's article "Affordance, Conventions, and Design" in Interactions, volume vi.3 (ACM 1072-5220/99/0500).
An object's visual appearance suggests its use.
A visual clue to the function of an object. Examples of affordance might be a sliver plate on the side of the door that you need you need to push to open it or a "raised" look on a button on a website.
An affordance refers to a physical property of something that influences how it can be used. For example, the affordances of paper include its properties for being viewed, it's light weight, and so on. The nature of a handle on a door determine how one open the door -- by pulling, or pushing, or twisting, and so on.
The properties of an object that inform people how the object could be used. The term "perceived affordance" applies when the object properties are perceived in a way that differs from the real-world, physical properties, especially when the usage of the object depends on perceived rather than real-world properties.
Affordance can refer to either of two related but distinct concepts. The term is used in the fields of perceptual psychology, cognitive psychology, environmental psychology, industrial design, human–computer interaction, interaction design and artificial intelligence.