The quality or state of being green in color, or the state of being covered with vegetation and plants; also can mean environmental consciousness.
From 'green' plus the noun-forming suffix '-ness'. This suffix, from Old English, creates abstract nouns expressing qualities or states. The environmental meaning is modern, dating to the 1970s-80s.
Plants are green because of chlorophyll, which absorbs red and blue light but reflects green—so the 'greenness' we see is actually the light plants don't want, making green the ultimate color of waste!
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