The Collaborative International Dictionary of English v.0.48:

Clog \Clog\ (kl[o^]g), n. [OE. clogge clog, Scot. clag, n., a
   clot, v., to to obstruct, cover with mud or anything
   adhesive; prob. of the same origin as E. clay.]
   1. That which hinders or impedes motion; hence, an
      encumbrance, restraint, or impediment, of any kind.
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            All the ancient, honest, juridical principles and
            institutions of England are so many clogs to check
            and retard the headlong course of violence and
            opression.                            --Burke.
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   2. A weight, as a log or block of wood, attached to a man or
      an animal to hinder motion.
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            As a dog . . . but chance breaks loose,
            And quits his clog.                   --Hudibras.
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            A clog of lead was round my feet.     --Tennyson.
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   3. A shoe, or sandal, intended to protect the feet from wet,
      or to increase the apparent stature, and having,
      therefore, a very thick sole. Cf. Chopine.
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            In France the peasantry goes barefoot; and the
            middle sort . . . makes use of wooden clogs.
                                                  --Harvey.
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   Clog almanac, a primitive kind of almanac or calendar,
      formerly used in England, made by cutting notches and
      figures on the four edges of a clog, or square piece of
      wood, brass, or bone; -- called also a Runic staff, from
      the Runic characters used in the numerical notation.

   Clog dance, a dance performed by a person wearing clogs, or
      thick-soled shoes.

   Clog dancer.
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WordNet (r) 3.0 (2006):

clog dance
    n 1: a dance performed while wearing shoes with wooden soles;
         has heavy stamping steps [syn: clog dance, clog
         dancing, clog]