The Collaborative International Dictionary of English v.0.48:

Cushion \Cush"ion\ (k[oo^]sh"[u^]n), v. t. [imp. & p. p.
   Cushioned (-[u^]nd); p. pr. & vb. n. Cushioning.]
   1. To seat or place on, or as on a cushion.
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            Many who are cushioned on thrones would have
            remained in obscurity.                --Bolingbroke.
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   2. To furnish with cushions; as, to cushion a chaise.
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   3. To conceal or cover up, as under a cushion.
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   Cushioned hammer, a dead-stroke hammer. See under
      Dead-stroke.
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The Collaborative International Dictionary of English v.0.48:

Cushion \Cush"ion\ (k??sh"?n), n. [OE. cuischun, quisshen, OF.
   coissin, cuissin, F. coussin, fr. (assumed) LL. culcitinum,
   dim. of L. culcita cushion, mattress, pillow. See Quilt,
   and cf. Counterpoint a coverlet.]
   1. A case or bag stuffed with some soft and elastic material,
      and used to sit or recline upon; a soft pillow or pad.
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            Two cushions stuffed with straw, the seat to raise.
                                                  --Dryden.
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   2. Anything resembling a cushion in properties or use; as:
      (a) a pad on which gilders cut gold leaf;
      (b) a mass of steam in the end of the cylinder of a steam
          engine to receive the impact of the piston;
      (c) the elastic edge of a billiard table.
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   3. A riotous kind of dance, formerly common at weddings; --
      called also cushion dance. --Halliwell.
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   Cushion capital.(Arch.) A capital so sculptured as to
      appear like a cushion pressed down by the weight of its
      entablature.
      (b) A name given to a form of capital, much used in the
          Romanesque style, modeled like a bowl, the upper part
          of which is cut away on four sides, leaving vertical
          faces.

   Cushion star (Zool.) a pentagonal starfish belonging to
      Goniaster, Astrogonium, and other allied genera; -- so
      called from its form.
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WordNet (r) 3.0 (2006):

cushion
    n 1: a mechanical damper; absorbs energy of sudden impulses;
         "the old car needed a new set of shocks" [syn: shock
         absorber, shock, cushion]
    2: the layer of air that supports a hovercraft or similar
       vehicle
    3: a soft bag filled with air or a mass of padding such as
       feathers or foam rubber etc.
    v 1: protect from impact; "cushion the blow" [syn: cushion,
         buffer, soften]