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