Pun, the name given to a play upon words that agree or resemble each other in sound but differ in sense, a verbal quibble by means of which an incongruous and therefore ludicrous idea is unexpectedly shot into the sentence—as, for example, in the answer to the grave question, 'Is life worth living?'—'That depends on the liver.' We find this form of wit in Aristophanes and Cicero, and in old England it was not unknown even in the pulpit. The sermons of Bishop Andrewes and the Church History and other works of Thomas Fuller abound in puns of all degrees of goodness and badness; they meet us strangely enough even in the gravest situations in the tragedies of Shakespeare, and there is at least one in Liddell and Scott's Greek Lexicon. Dr Johnson said that the man who would make a pun would pick a pocket; but this sentence bears too hard upon the best beloved of English writers, Charles Lamb, a hardened punster, not to speak of Sydney Smith, Hook, Hood, the prince of punsters, and Bishop Wilberforce. Boswell, while relating Dr Johnson's dislike to puns, ventures his own opinion that 'a good pun may be admitted among the smaller excellencies of conversation.' But a pun of the best kind has a value infinitely higher than this: there is tenderness as well as wit in Fuller's phrase of the Holy Innocents of Bethlehem—'the infantry in the noble army of martyrs.'
See Spectator, No. 61, L. Larchey's Les Joueurs des Mots (1866), and Holmes's Autoerat of the Breakfast Table. The Hon. Hugh Rowley's Puniana (1867) and More Puniana (1875) contain many hundred examples, among them a few good puns.