Jack, a word with a great variety of meanings and applications, all traceable to the common use of the word as a by-name of a man. The question has been much discussed whether “Jack” as a name is an adaptation of Fr. Jacques, i.e. James, from Lat. Jacobus, Gr. Ἰάκωβος, or whether it is a direct pet formation from John, which is its earliest and universal use in English. In the History of the Monastery of St Augustine at Canterbury, 1414, Jack is given as a form of John—Mos est Saxonum ... verba et nomina transformare ... ut ... pro Johanne Jankin sive Jacke (see E. W. B. Nicholson, The Pedigree of Jack and other Allied Names, 1892). “Jack” was early used as a general term for any man of the common people, especially in combination with the woman’s name Jill or Gill, as in the nursery rhyme. The New English Dictionary quotes from the Coventry Mysteries, 1450: “And I wole kepe the feet this tyde Thow ther come both Iakke and Gylle.” Familiar examples of this generic application of the name are Jack or Jack Tar for a sailor, which seems to date from the 17th century, and such compound uses as cheap-jack and steeple-jack, or such expressions as “jack in office,” “jack of all trades,” &c. It is a further extension of this that gives the name to the knave in a pack of cards, and also to various animals, as jackdaw, jack-snipe, jack-rabbit (a species of large prairie-hare); it is also used as a general name for pike.
The many applications of the word “jack” to mechanical devices and other objects follow two lines of reference, one to objects somewhat smaller than the ordinary, the other to appliances which take the place of direct manual labour or assist or save it. Of the first class may be noticed the use of the term for the small object bowl in the game of bowls or for jack rafters, those rafters in a building shorter than the main rafters, especially the end rafters in a hipped roof. The use of jack as the name for a particular form of ship’s flag probably arose thus, for it is always a smaller flag than the ensign. The jack is flown on a staff on the bowsprit of a vessel. In the British navy the jack is a small Union flag. (The Union flag should not be styled a Union Jack except when it is flown as a jack.) The jack of other nations is usually the canton of the ensign, as in the German and the United States navies, or else is a smaller form of the national ensign, as in France. (See Flag.)
The more common use of “jack” is for various mechanical and other devices originally used as substitutes for men or boys. Thus the origin of the boot-jack and the meat-jack is explained in Isaac Watts’s Logic, 1724: “So foot boys, who had frequently the common name of Jack given them, were kept to turn the spit or pull off their masters’ boots, but when instruments were invented for both these services, they were both called jacks.” The New English Dictionary finds a transitional sense in the use of the name “jack” for mechanical figures which strike the hours on a bell of a clock. Such a figure in the clock of St Lawrence Church at Reading is called a jack in the parish accounts for 1498-1499. There are many different applications of “jack,” to certain levers and other parts of textile machinery, to metal plugs used for connecting lines in a telephone exchange, to wooden uprights connecting the levers of the keys with the strings in the harpsichord and virginal, to a framework forming a seat or staging which can be fixed outside a window for cleaning or painting purposes, and to many devices containing a roller or winch, as in a jack towel, a long towel hung on a roller. The principal mechanical application of the word, however, is to a machine for raising weights from below. A jack chain, so called from its use in meat-jacks, is one in which the links, formed each in a figure of eight, are set in planes at right angles to each other, so that they are seen alternately flat or edgeways.
In most European languages the word “jack” in various forms appears for a short upper outer garment, particularly in the shape of a sleeveless (quilted) leather jerkin, sometimes with plates or rings of iron sewn to it. It was the common coat of defence of the infantry of the middle ages. The word in this case is of French origin and was an adaptation of the common name Jacques, as being a garment worn by the common people. In French the word is jaque, and it appears in Italian as giaco, or giacco, in Dutch jak, Swedish jacka and German Jacke, still the ordinary name for a short coat, as is the English jacket, from the diminutive French jaquette. It was probably from some resemblance to the leather coat that the well-known leather vessels for holding liquor or for drinking were known as jacks or black jacks. These drinking vessels, which are often of great size, were not described as black jacks till the 16th century, though known as jacks much earlier. Among the important specimens that have survived to this day is one with the initials and crown of Charles I. and the date, 1646, which came from Kensington Palace and is now in the British Museum; one each at Queen’s College and New College, Oxford; two at Winchester College; one at Eton College; and six at the Chelsea Hospital. Many specimens are painted with shields of arms, initials and other devices; they are very seldom mounted in silver, though spurious specimens with silver medallions of Cromwell and other prominent personages exist. At the end of the 17th century a smaller jack of a different form, like an ordinary drinking mug with a tapering cylindrical body, often mounted in silver, came into vogue in a limited degree. The black jack is a distinct type of drinking vessel from the leather botel and the bombard. The jack-boot, the heavy riding boot with long flap covering the knee and part of the thigh, and worn by troopers first during the 17th century, was so called probably from association with the leather jack or jerkin. The jack-boot is still worn by the Household Cavalry, and the name is applied to a high riding boot reaching to the knee as distinguished from the riding boot with tops, used in full hunting-kit or by grooms or coachmen.
Jack, sometimes spelled jak, is the common name for the fruit of the tree Artiocarpus integrifolia, found in the East Indies. The word is an adaptation of the Portuguese jaca from the Malay name chakka. (See Bread Fruit.)
The word “jackanapes,” now used as an opprobrious term for a swaggering person with impertinent ways and affected airs and graces, has a disputed and curious history. According to the New English Dictionary it first appears in 1450 in reference to William de la Pole, duke of Suffolk (Political Poems, “Rolls Series,” II. 224), “Jack Napys with his clogge hath tiede Talbot oure gentille dogge.” Suffolk’s badge was a clog and chain, such as was often used for an ape kept in captivity, and he is alluded to (ibid. 222) as “Ape clogge.” Jack Napes, Jack o’ Napes, Jackanapes, was a common name for a tame ape from the 16th century, and it seems more likely that the word is a fanciful name for a monkey than that it is due to the nickname of Suffolk.
