c.1300, "a shoot or twig," from O.Fr. sion, cion (Mod.Fr. scion, Picard chion), of uncertain origin. Perhaps from Frankish *kid-, from P.Gmc. *kidon-, from PIE *geie- "to sprout, split, open." Figurative use is attested from 1580s; meaning "an heir, a descendant" is from 1814, from the "family tree" image.