Definition of greenest:
(n) :
The color of grass and leaves; a primary additive color midway between yellow and blue which is evoked by light between roughly 495–570 nm.
(n) :
(politics, sometimes capitalized) A member of a green party; an environmentalist.
(n) :
(golf) A putting green, the part of a golf course near the hole.
(n) :
(bowls) The surface upon which bowls is played.
(n) :
(snooker) One of the color balls used in snooker, with a value of 3 points.
(n) :
(British) A public patch of land in the middle of a settlement.