The Collaborative International Dictionary of English v.0.48:

Post \Post\, n. [AS., fr. L. postis, akin to ponere, positum, to
   place. See Position, and cf. 4th Post.]
   1. A piece of timber, metal, or other solid substance, fixed,
      or to be fixed, firmly in an upright position, especially
      when intended as a stay or support to something else; a
      pillar; as, a hitching post; a fence post; the posts of a
      house.
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            They shall take of the blood, and strike it on the
            two side posts and on the upper doorpost of the
            houses.                               --Ex. xii. 7.
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            Then by main force pulled up, and on his shoulders
            bore,
            The gates of Azza, post and massy bar. --Milton.
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            Unto his order he was a noble post.   --Chaucer.
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   Note: Post, in the sense of an upright timber or strut, is
         used in composition, in such words as king-post,
         queen-post, crown-post, gatepost, etc.
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   2. The doorpost of a victualer's shop or inn, on which were
      chalked the scores of customers; hence, a score; a debt.
      [Obs.]
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            When God sends coin
            I will discharge your post.           --S. Rowlands.
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   From pillar to post. See under Pillar.

   Knight of the post. See under Knight.

   Post hanger (Mach.), a bearing for a revolving shaft,
      adapted to be fastened to a post.

   Post hole, a hole in the ground to set the foot of a post
      in.

   Post mill, a form of windmill so constructed that the whole
      fabric rests on a vertical axis firmly fastened to the
      ground, and capable of being turned as the direction of
      the wind varies.

   Post and stall (Coal Mining), a mode of working in which
      pillars of coal are left to support the roof of the mine.
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WordNet (r) 3.0 (2006):

post hole
    n 1: a hole dug in the ground to hold a fence post [syn:
         posthole, post hole]