The Collaborative International Dictionary of English v.0.48:
Jack \Jack\ (j[a^]k), n. [F. Jacques James, L. Jacobus, Gr. ?,
Heb. Ya 'aq[=o]b Jacob; prop., seizing by the heel; hence, a
supplanter. Cf. Jacobite, Jockey.]
1. A familiar nickname of, or substitute for, John.
You are John Rugby, and you are Jack Rugby. --Shak.
2. An impertinent or silly fellow; a simpleton; a boor; a
clown; also, a servant; a rustic. "Jack fool." --Chaucer.
Since every Jack became a gentleman,
There 's many a gentle person made a Jack. --Shak.
3. A popular colloquial name for a sailor; -- called also
Jack tar, and Jack afloat.
4. A mechanical contrivance, an auxiliary machine, or a
subordinate part of a machine, rendering convenient
service, and often supplying the place of a boy or
attendant who was commonly called Jack; as:
(a) A device to pull off boots.
(b) A sawhorse or sawbuck.
(c) A machine or contrivance for turning a spit; a smoke
jack, or kitchen jack.
(b) (Mining) A wooden wedge for separating rocks rent by
(e) (Knitting Machine) A lever for depressing the sinkers
which push the loops down on the needles.
(f) (Warping Machine) A grating to separate and guide the
threads; a heck box.
(g) (Spinning) A machine for twisting the sliver as it
leaves the carding machine.
(h) A compact, portable machine for planing metal.
(i) A machine for slicking or pebbling leather.
(k) A system of gearing driven by a horse power, for
(l) A hood or other device placed over a chimney or vent
pipe, to prevent a back draught.
(m) In the harpsichord, an intermediate piece
communicating the action of the key to the quill; --
called also hopper.
(n) In hunting, the pan or frame holding the fuel of the
torch used to attract game at night; also, the light
itself. --C. Hallock.
5. A portable machine variously constructed, for exerting
great pressure, or lifting or moving a heavy body such as
an automobile through a small distance. It consists of a
lever, screw, rack and pinion, hydraulic press, or any
simple combination of mechanical powers, working in a
compact pedestal or support and operated by a lever,
crank, capstan bar, etc. The name is often given to a
jackscrew, which is a kind of jack.
6. The small bowl used as a mark in the game of bowls.
Like an uninstructed bowler who thinks to attain the
jack by delivering his bowl straight forward upon
it. --Sir W.
7. The male of certain animals, as of the ass.
(a) A young pike; a pickerel.
(b) The jurel.
(c) A large, California rock fish (Sebastodes
paucispinus); -- called also boccaccio, and
(d) The wall-eyed pike.
9. A drinking measure holding half a pint; also, one holding
a quarter of a pint. [Prov. Eng.] --Halliwell.
(a) A flag, containing only the union, without the fly,
usually hoisted on a jack staff at the bowsprit cap;
-- called also union jack. The American jack is a
small blue flag, with a star for each State.
(b) A bar of iron athwart ships at a topgallant masthead,
to support a royal mast, and give spread to the royal
shrouds; -- called also jack crosstree. --R. H.
11. The knave of a suit of playing cards.
12. (pl.) A game played with small (metallic, with
tetrahedrally oriented spikes) objects (the jacks(1950+),
formerly jackstones) that are tossed, caught, picked up,
and arranged on a horizontal surface in various patterns;
in the modern American game, the movements are
accompanied by tossing or bouncing a rubber ball on the
horizontal surface supporting the jacks. same as
13. Money. [slang]
14. Apple jack.
Note: Jack is used adjectively in various senses. It
sometimes designates something cut short or diminished
in size; as, a jack timber; a jack rafter; a jack arch,
Jack arch, an arch of the thickness of one brick.
Jack back (Brewing & Malt Vinegar Manuf.), a cistern which
receives the wort. See under 1st Back.
Jack block (Naut.), a block fixed in the topgallant or
royal rigging, used for raising and lowering light masts
Jack boots, boots reaching above the knee; -- worn in the
17 century by soldiers; afterwards by fishermen, etc.
Jack crosstree. (Naut.) See 10, b, above.
Jack curlew (Zool.), the whimbrel.
Jack frame. (Cotton Spinning) See 4
Jack Frost, frost or cold weather personified as a
Jack hare, a male hare. --Cowper.
Jack lamp, a lamp for still hunting and camp use. See def.
Jack plane, a joiner's plane used for coarse work.
Jack post, one of the posts which support the crank shaft
of a deep-well-boring apparatus.
Jack pot (Poker Playing), the name given to the stakes,
contributions to which are made by each player
successively, till such a hand is turned as shall take the
"pot," which is the sum total of all the bets. See also
Jack rabbit (Zool.), any one of several species of large
American hares, having very large ears and long legs. The
California species (Lepus Californicus), and that of
Texas and New Mexico (Lepus callotis), have the tail
black above, and the ears black at the tip. They do not
become white in winter. The more northern prairie hare
(Lepus campestris) has the upper side of the tail white,
and in winter its fur becomes nearly white.
Jack rafter (Arch.), in England, one of the shorter rafters
used in constructing a hip or valley roof; in the United
States, any secondary roof timber, as the common rafters
resting on purlins in a trussed roof; also, one of the
pieces simulating extended rafters, used under the eaves
in some styles of building.
Jack salmon (Zool.), the wall-eyed pike, or glasseye.
Jack sauce, an impudent fellow. [Colloq. & Obs.]
Jack shaft (Mach.), the first intermediate shaft, in a
factory or mill, which receives power, through belts or
gearing, from a prime mover, and transmits it, by the same
means, to other intermediate shafts or to a line shaft.
Jack sinker (Knitting Mach.), a thin iron plate operated by
the jack to depress the loop of thread between two
Jack snipe. (Zool.) See in the Vocabulary.
Jack staff (Naut.), a staff fixed on the bowsprit cap, upon
which the jack is hoisted.
Jack timber (Arch.), any timber, as a rafter, rib, or
studding, which, being intercepted, is shorter than the
Jack towel, a towel hung on a roller for common use.
Jack truss (Arch.), in a hip roof, a minor truss used where
the roof has not its full section.
Jack tree. (Bot.) See 1st Jack, n.
Jack yard (Naut.), a short spar to extend a topsail beyond
Blue jack, blue vitriol; sulphate of copper.
Hydraulic jack, a jack used for lifting, pulling, or
forcing, consisting of a compact portable hydrostatic
press, with its pump and a reservoir containing a supply
of liquid, as oil.
(a) One called upon to take the place of another in an
(b) An itinerant parson who conducts an occasional
service for a fee.
Jack-at-all-trades, one who can turn his hand to any kind
Jack-by-the-hedge (Bot.), a plant of the genus Erysimum
(Erysimum alliaria, or Alliaria officinalis), which
grows under hedges. It bears a white flower and has a
taste not unlike garlic. Called also, in England,
sauce-alone. --Eng. Cyc.
Jack-in-office, an insolent fellow in authority. --Wolcott.
Jack-in-the-bush (Bot.), a tropical shrub with red fruit
Jack-in-the-green, a chimney sweep inclosed in a framework
of boughs, carried in Mayday processions.
Jack-of-the-buttery (Bot.), the stonecrop (Sedum acre).
Jack-of-the-clock, a figure, usually of a man, on old
clocks, which struck the time on the bell.
Jack-on-both-sides, one who is or tries to be neutral.
Jack-out-of-office, one who has been in office and is
turned out. --Shak.
Jack the Giant Killer, the hero of a well-known nursery
Yellow Jack (Naut.), the yellow fever; also, the quarantine
flag. See Yellow flag, under Flag.