See also #usable.
Definitions:
Capability of a product to have specified users learn to use specified product functions within a specified amount of time.
Capability of a product to have specified users learn to use specified product functions within a specified amount of time.
Requirements specifying how easy it should be to learn to use the product. This learning curve ranges from zero time for products intended for placement in the public domain (e.g., a parking meter or a web site) to a considerable amount of time for complex, highly technical products. (We know of one product where it was necessary for graduate engineers to spend 18 months in a training program before being qualified to use the product.)