Accessibility

n. approachability; openness

For Wikipedia's accessibility policy, see Wikipedia:Accessibility. For the wider concept of universal design, see universal design. In logic, the accessibility relation between possible worlds.Accessibility is a general term used to describe the degree to which a system is usable by as many people as possible. In other words, it is the degree of ease with which it is possible to reach a certain location from other locations. It is not to be confused with usability which is used to describe how easily an entity (e.g., device, service, environment) can be used by any type of user. Accessibility can also be viewed as the "ability to access" the functionality, and possible benefit, of some system or entity; such a definition brings in access-based individual rights laws and regulations that are discussed below. One meaning of accessibility specifically focuses on people with disabilities and their right of access to entities, often through use of assistive devices such as screen-reading web browsers or wheelchairs. Other meanings are discussed below.
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(n.)
The quality of being accessible, or of admitting approach; receptibility.
  

one of the four major requirements (with actionability, measurability and substantiality) for useful market segmentation; accessibility expresses the notion that the segment targeted must be able to be reached and served adequately by the firm's promotion and distribution system. See Actionability; Measurability; Substantiality.