A male name. this, the commonest pet-name for John (q.v.), has caused a good deal of difficulty owing to the natural assumption that it must be derived from the French Jacques and should therefore logically represent James rather than John. The problem was cleared up by E. W. B. Nicholson in a little book entitled The Pedigree of Jack and of Various Allied Names (l892), He showed that there is no recorded instance of Jack, Jak, Jacke, or Jakke ever being used to represent Jacques or James, and that no statement in favour of the French connexion has been produced from any early writer. He then proceeded to elucidate and illustrate with examples the development from Johannes to Jehan and Jan, whence, by addition of the common suffix -kin, we get Jankin, which as a result of French nasalization becomes Jackin, and was finally shortened to Jack. There was a similar development from Jon to Jock (the Scottish form of the name). This process was complete by the beginning of the 14th C, by which time Jack was already established as a synonym for man or boy. The Oxford English Dictionary gives no fewer than 80 uses and compounds of jack as a common noun. The correctness of this derivation of Jack is confirmed by a passage in the Historia Monasterii S. Augustini Cantuariensis c. 1414: ‘Mos enim est barbaricae locutionis et Saxonum, et si non transponere, transformare tamen apocopando, et saepius syncopando: ut pro Thoma Tomme seu Tomlin; pro Johanne Jankin sive Jacke.’

The usual diminutive or, rather, pet-form of John, it is sometimes bestowed independently. It is frequently used in names personifying human types and non-human aspects: the Australian jackaroo, modelled on kangaroo; Jack Frost; Jack Adams; Jack Robinson; Jack Sprat; Jack a’ Lent, the Shakespearean equivalent of Sally. ‘To enumerate all the transferred and colloquial senses of Jack, continues Professor Weekley (in W. & N.), ‘would require a fair-sized book. As applied to people it is usually contemptuous or hostile... Even Jack Tar, now admirative, was... originally used by those who thought, with Dr. Johnson, that no man ever went to sea who had wit enough to get himself inside a gaol.’ (See also my Unconventional English.)