open source

Short definition from Wiktionary

Noun

1. 1
   The practice of providing open-source code for a product.
2. 2
   Open-source software in general.
3. 3
   Information that is in the public domain and available to everybody.

Verb

1. 1
   Alternative form of open-source.
2. 2
   To release the source code of, so as to permit modification and redistribution.

Adjective

1. 1
   Of or relating to software where the source code is freely available and licensed in a manner that permits modification and redistribution.
2. 2
   Describing any product whose composition or method of manufacturing is public knowledge and not proprietary.
3. 3
   Relying on publicly available information (open sources).