Etymology
1. O.E.
grene, earlier
groeni, related to O.E.
growan "to grow," from W.Gmc.
*gronja- (cf. O.Fris.
grene, O.N.
grænn, Dan.
grøn, Du.
groen, Ger.
grün), from PIE base
*gro- "grow," through sense of "color of living plants." The color of jealousy at least since Shakespeare (1596);
"Greensleeves," ballad of an inconstant lady-love, is from 1580. Meaning of "a field, grassy place" was in O.E. Sense of "of tender age, youthful" is from 1412; hence "gullible" (1605).
Greenhorn (containing the sense of "new, fresh, recent") was first "young horned animal" (1455), then "recently enlisted soldier" (1650), then "any inexperienced person" (1682).
Green light in figurative sense of "permission" is from 1937. Green and red as signals on railways first attested 1883, as nighttime substitutes for semaphore flags.
Green beret originally "British commando" is from 1949.
Green room "room for actors when not on stage" is from 1701; presumably a well-known one was painted green.
2. From Middle English grenen, from Old English grēnian (“to become green, flourish”), from Proto-West Germanic *grōnijan, from Proto-Germanic *grōnijōną, *grōnijaną (“to become green”), from the adjective (see above).
3. Cognate with Saterland Frisian gräinje, German Low German grönen, German grünen, Swedish gröna, Icelandic gróna. See: Frisian, Saterlandic 'gräinje', German, old spelling '
grünen', Swedish '
gröna', Icelandic '
gróna'.