ungreen
To expose to air after dyeing in indigo so that the greenish color fades away.
When necessary to air and ungreen, by drawing the pulley the frame rises, and the cloth drains into the vat.
To make or become familiar with and adept in handling a new environment.
Freshmen are called greens, and a ceremony was (and perhaps is) used in ungreening them, and admitting them to their full academical privileges.
To change from green to some other color, as occurs with leaves in the autumn.
Harvests are congratulated She is pleased with the sight, Sweet hard apples and Small ungreening leaves.
To urbanize or become less environmentally friendly.
John Robinson, in “Highways and Our Environment," complains that the highway system not only has disfigured our countryside by slapping down acres of concrete that threatens to ungreen America, but also carries an increasing number of cars that further befoul the environment by thrusting more pollutants into the air.
Where it comes from
From Middle English ungrene, from Old English ungrēne (“not green”), from Proto-West Germanic *ungrōnī (“not green”), equivalent to un- + green. Compare West Frisian ûngrien (“ungreen”), Dutch ongroen (“ungreen”), German ungrün (“not green”), Danish ugrøn (“ungreen”), Swedish ogrön (“ungreen”), Icelandic ógræn (“ungreen”).
Adapted from the Wiktionary entry ungreen (CC BY-SA 4.0).