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.
   [1913 Webster]

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"

Moby Thesaurus II by Grady Ward, 1.0:

65 Moby Thesaurus words for "pun":
   abuse of terms, acrostic, alliterate, alliteration, ambiguity,
   amphibologism, amphibology, amphiboly, anagram, assonance,
   assonate, be merry with, calembour, chime, clink, corruption,
   counterword, crack a joke, crack wise, double entendre, equivocal,
   equivocality, equivocation, equivoque, fleer at, fun, gibe at,
   jape, jest, jeu de mots, jingle, joke, josh, kid, kid around,
   logogram, logogriph, make a funny, make fun, make fun of,
   malapropism, metagram, missaying, mock, near rhyme, palindrome,
   paronomasia, play on words, poke fun at, polysemant,
   portmanteau word, punning, quip, rhyme, ridicule, scintillate,
   scoff at, slant rhyme, sparkle, spoonerism, squinting construction,
   utter a mot, weasel word, wisecrack, wordplay