green (adj.)

Old English grene, Northumbrian groene “green, of the color of living plants,” in reference to plants, “growing, living, vigorous,” also figurative, of a plant, “freshly cut,” of wood, “unseasoned” earlier groeni, from Proto-Germanic *grōni- (source also of Old Saxon grani, Old Frisian grene, Old Norse grænn, Danish grøn, Dutch groen, Old High German gruoni, German grün), from PIE root *ghre- “grow” (see grass), through sense of “color of growing plants.”

grass (n.)

Old English græs, gærs “herb, plant, grass,” from Proto-Germanic *grasan, which, according to Watkins, is from PIE *ghros- “young shoot, sprout,” from root *ghre- “to grow, become green,” thus related to grow and green, but not to Latin grāmen “grass, plant, herb.”

grow (v.)

Middle English grouen, from Old English growan (of plants) “to flourish, increase, develop, get bigger” (class VII strong verb; past tense greow, past participle growen), from Proto-Germanic *gro-, from PIE root *ghre- “to grow, become green” (see grass).

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