The Collaborative International Dictionary of English v.0.48:

Scion \Sci"on\, n. [OF. cion, F. scion, probably from scier to
   saw, fr. L. secare to cut. Cf. Section.]
   1. (Bot.)
      (a) A shoot or sprout of a plant; a sucker.
      (b) A piece of a slender branch or twig cut for grafting.
          [Formerly written also cion, and cyon.]
          [1913 Webster]

   2. Hence, a descendant; an heir; as, a scion of a royal
      stock.
      [1913 Webster]

WordNet (r) 3.0 (2006):

scion
    n 1: a descendent or heir; "a scion of royal stock"

Moby Thesaurus II by Grady Ward, 1.0:

62 Moby Thesaurus words for "scion":
   appendage, arm, bine, bough, branch, branchedness, branchiness,
   burgeon, child, daughter, deadwood, descendant, flagellum, fork,
   foster child, frond, grandchild, granddaughter, grandson, hand,
   heiress, imp, joint, leg, limb, link, lobe, lobule, member,
   offshoot, offspring, organ, pinion, ramage, ramification, runner,
   sapling, sarment, seedling, set, shoot, slip, son, son and heir,
   sonny, spear, spray, sprig, sprit, sprout, spur, stepchild,
   stepdaughter, stepson, stolon, sucker, switch, tail, tendril,
   thallus, twig, wing