You hear the word 'intuitive' thrown about often when speaking of UX and Usability.
The definition I hate the most is "Something is intuitive if you can figure it out without documentation or explanation." I hate this definition because it often leads to cluttered interfaces that try to tell you too much that you won't care about after you've used the interface a couple of times.
In my experience there are three difference concepts that shouldn't be confused: intuitive design, discoverable design, and recognizable cognitive models.
Intuitive Design - I normally define intuitive as ... "being shown once the interaction is understood and easily remembered for subsequent use" e.g. the first time you saw a computer mouse you didn't know what it was for, but quickly the idea of the movement of the mouse corresponding to the movement of a cursor on the screen and then an action button to interact with what the mouse is targeting is easy to understand and remember.
Discoverable Design - I normally define discoverable as ... "elements of the interface that draw the eye and invite exploration for discovery of function" e.g. In the pre-flat interface days a widget was shadowed and had texture to make it obvious it could be interacted with.
Recognizable Cognitive Models - I normally define a recognizable cognitive model as ... "borrowing an idea that is commonly understood and has an expected set of interactions" e.g. A shopping cart is now a recognizable cognitive model and people generally understand that they can put things in it, review and remove things from it, and purchase the contents.
What definitions do you use? Anyone have any to add?