Defining the "Open" in Open Content and Open Educational Resources:
The terms "open content" and "open educational resources" describe any copyrightable work (traditionally excluding software, which is described by other terms like "open source") that is licensed in a manner that provides users with free and perpetual permission to engage in the 5R activities:

• Retain - the right to make, own, and control copies of the content (e.g., download, duplicate, store, and manage).
• Reuse - the right to use the content in a wide range of ways (e.g., in a class, in a study group, on a website, in a video).
• Revise - the right to adapt, adjust, modify, or alter the content itself (e.g., translate the content into another language).
• Remix - the right to combine the original or revised content with other material to create something new (e.g., incorporate the content into a mashup).
• Redistribute - the right to share copies of the original content, your revisions, or your remixes with others (e.g., give a copy of the content to a friend).
  This material was created by David Wiley and published freely under a Creative Commons Attribution 4.0 license at http://opencontent.org/definition/.