1. ungreen - Adjective
2. ungreen - Verb
(uncommon) Not green.
Having little or no vegetation or plant matter.
Lacking sap or vitality; desiccated.
Environmentally unfriendly; harmful to or inconsiderate of the environment.
(dyeing) To expose to air after dyeing in indigo so that the greenish color fades away.
To make or become familiar with and adept in handling a new environment.
To change from green to some other color, as occurs with leaves in the autumn.
To urbanize or become less environmentally friendly.
Source: en.wiktionary.org