Noun
A garden enclosed by walls for purposes of shelter or decoration.
(figuratively, media, technology) A closed platform for content or services controlled by a single carrier or service provider, typically requiring subscription to access.
Synonym: closed platform
(Internet) A set of webpages or other resources that are richly interlinked and share a common focus, but have little or no linkage to or from the larger network.
Source: en.wiktionary.org