green

green traditionally the colour of jealousy, green is also taken to symbolize youth and immaturity.

In 20th century use, green (often with a capital initial) means concerned with or supporting protection of the environment as a political principle.
Reverend Green is the name of one of the six stock characters constituting the murderer and suspects in the game of Cluedo.
green belt an area of open land around a city, on which building is restricted. A green belt also marks a level of proficiency in judo, karate, or other martial arts below that of a brown belt.
Green Beret a British commando or a member of the US Army Special Forces.
Green Book in England and Wales, a book setting out the procedural rules of the county courts, bound in green.
green card in the US, a permit allowing a foreign national to live and work permanently in the US.
the green-eyed monster jealousy personified; originally from Iago's warning in Shakespeare's Othello, ‘O! beware, my lord, of jealousy; It is the green-eyed monster which doth mock The meat it feeds on.’
green fingers natural ability in growing plants; recorded from the 1930s.
green light a signal that one may proceed with one's chosen course; often in give the green light to. The allusion is to a green light in traffic signals.
green man a man dressed up in greenery to represent a wild man of the woods or seasonal fertility. A carved image of this is often seen in medieval English churches, as a human face with branches and foliage growing out of the mouth.
Green Mountain State an informal name for Vermont.
Green Paper in the UK, a preliminary report of government proposals that is published in order to provoke discussion.
Green Party an environmentalist political party. Green Parties arose in Europe in the early 1970s, since when they have achieved a certain amount of electoral success, particularly in Germany. The Green Party in Britain was founded in 1973 as the Ecology Party, changing its name in 1985.
green room a room in a theatre or studio in which performers can relax when they are not performing. The name probably derives from the room's originally being painted green. The first reference to it is in Love Makes a Man (1701), a play by Colley Cibber.
green shoots signs of growth or renewal, especially of economic recovery. The expression in this context derives from a misquotation, ‘the green shoots of recovery’, of a speech made by the Conservative politician Norman Lamont when Chancellor in 1991, when he said that, ‘The green shoots of economic spring are appearing once again.’
Green Thursday another name for Maundy Thursday, perhaps referring to the practice of giving green branches to penitents who had made their confession on Ash Wednesday.
a green Yule makes a fat churchyard a mild winter is traditionally unhealthy; saying recorded from the mid 17th century.
Green Zone an area in central Baghdad which is the base for representatives of the coalition and the Iraqi interim government; it is subject to a high level of security.

See also the grass is always greener, little green man, believe that the moon is made of green cheese.