The Collaborative International Dictionary of English v.0.48:

Stanchion \Stan"chion\ (st[a^]n"sh[u^]n; 277), n. [OF. estanson,
   estan[,c]on, F. ['e]tan[,c]on, from OF. estance a stay, a
   prop, from L. stans, stantis, standing, p. pr. of stare to
   stand. See Stand, and cf. Stanza.] [Written also
   stanchel.]
   1. (Arch.) A prop or support; a piece of timber in the form
      of a stake or post, used for a support or stay.
      [1913 Webster]

   2. (Naut.) Any upright post or beam used as a support, as for
      the deck, the quarter rails, awnings, etc.
      [1913 Webster]

   3. A vertical bar for confining cattle in a stall.
      [1913 Webster]

WordNet (r) 3.0 (2006):

stanchion
    n 1: any vertical post or rod used as a support

Moby Thesaurus II by Grady Ward, 1.0:

47 Moby Thesaurus words for "stanchion":
   Samson post, baluster, balustrade, banister, base, caryatid,
   colonnade, column, dado, die, doorjamb, doorpost, footstalk,
   gatepost, hitching post, jack, jamb, king post, milepost, mullion,
   newel-post, pedestal, pedicel, peduncle, pier, pilaster, pile,
   piling, pillar, plinth, pole, post, queen-post, shaft, signpost,
   snubbing post, socle, staff, stalk, stand, standard, stem, stile,
   subbase, surbase, trunk, upright