galusha a. grow

O.E. growan (of plants) "to flourish, develop, get bigger" (class VII strong verb; past tense greow, pp. growen), from P.Gmc. *gro- (cf. O.N. groa, O.Fris. groia, Du. groeien, O.H.G. gruoen), from root of grass (q.v.). Applied in M.E. to human beings (c.1300) and animals (1435) and their parts, supplanting O.E. weaxan (see wax (v.)).

"Have you ever heard anything about God, Topsy? ... Do you know who made you?" "Nobody, as I knows on," said the child. ... "I spect I grow'd. Don't think nobody never made me." [Harriet B. Stowe, "Uncle Tom's Cabin," 1851]

Grown-up (adj.) "mature" is from 1633; the noun meaning "adult person" is from 1813. Growth is first attested 1557, on model of health, stealth, etc.