"shoot inserted into another plant," late 15c. alteration of Middle English graff (late 14c.), from Old French graife "grafting knife, carving tool; stylus, pen," from Latin graphium "stylus," from Greek grapheion "stylus," from graphein "to write" (see -graphy). So called probably on resemblance of a stylus to the pencil-shaped shoots used in grafting. The terminal -t in the English word is not explained. Surgical sense is from 1871.
"corruption," 1865, perhaps 1859, American English, perhaps from British slang graft "one's occupation" (1853), which is perhaps from the identical word meaning "a ditch, moat," literally "a digging" (1640s), from Middle Dutch graft, from graven "to dig" (see grave (v.)).
late 15c., "insert a shoot from one tree into another," from graft (n.1). Figurative use by 1530s. Surgical sense by 1868. Related: Grafted; grafting.