1) The term greenfield was originally used in construction and
development to reference land that has never been used (e.g. green or new),
where there was no need to demolish or rebuild any existing structures.
Today, the term greenfield project is used in many industries, including
software development where it means to start a project without the need to
consider any prior work.
Contrast with brownfield.
2) In wireless LAN (WLAN) technology, greenfield mode is a feature
of major components of the 802.11n specification. The greenfield mode feature is
designed to improve efficiency by eliminating support for
802.11a/b/g devices in
an all draft-n network. In greenfield
mode the network can be set to ignore all
earlier standards.