The Collaborative International Dictionary of English v.0.48:

Pun \Pun\, v. i. [imp. & p. p. Punned; p. pr. & vb. n.
   Punning.]
   To make puns, or a pun; to use a word in a double sense,
   especially when the contrast of ideas is ludicrous; to play
   upon words; to quibble. --Dryden.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Pun \Pun\, v. t.
   To persuade or affect by a pun. --Addison.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Pun \Pun\, v. t. [See Pound to beat.]
   To pound. [Obs.]
   [1913 Webster]

         He would pun thee into shivers with his fist. --Shak.
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The Collaborative International Dictionary of English v.0.48:

Pun \Pun\, n. [Cf. Pun to pound, Pound to beat.]
   A play on words which have the same sound but different
   meanings; an expression in which two different applications
   of a word present an odd or ludicrous idea; a kind of quibble
   or equivocation. --Addison.
   [1913 Webster]

         A better put on this word was made on the Beggar's
         Opera, which, it was said, made Gay rich, and Rich gay.
                                                  --Walpole.
   [1913 Webster]

WordNet (r) 3.0 (2006):

pun
    n 1: a humorous play on words; "I do it for the pun of it"; "his
         constant punning irritated her" [syn: pun, punning,
         wordplay, paronomasia]
    v 1: make a play on words; "Japanese like to pun--their language
         is well suited to punning"