The Collaborative International Dictionary of English v.0.48:

Club \Club\ (kl[u^]b), v. t. [imp. & p. p. Clubbed (kl[u^]bd);
   p. pr. & vb. n. Clubbing.]
   1. To beat with a club.
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   2. (Mil.) To throw, or allow to fall, into confusion.
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            To club a battalion implies a temporary inability in
            the commanding officer to restore any given body of
            men to their natural front in line or column.
                                                  --Farrow.
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   3. To unite, or contribute, for the accomplishment of a
      common end; as, to club exertions.
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   4. To raise, or defray, by a proportional assesment; as, to
      club the expense.
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   To club a musket (Mil.), to turn the breach uppermost, so
      as to use it as a club.
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WordNet (r) 3.0 (2006):

clubbing
    n 1: a condition in which the ends of toes and fingers become
         wide and thick; a symptom of heart or lung disease