Open Source
Dictionary Definition
1. (general) Pertaining to or denoting a product or system whose origins, formula, design, etc., are freely accessible to the public.
2. (software) Pertaining to or denoting software whose source code is available free of charge to the public to use, copy, modify, sublicense, or distribute
http://dictionary.reference.com/browse/open+source?s=t
Committee Definition
Needs contribution
Domain Specific Usage
From a software perspective, Open Source Initiative specifically state distribution terms of open source software at http://opensource.org/definition.
Notes
A list of software licenses that comply with the Open Source Initiative definition of "open source" is available at http://opensource.org/licenses.