Jack (?), n. [F. Jacques James,
L. Jacobus, Gr. ?, Heb. Ya 'aqōb Jacob; prop.,
seizing by the heel; hence, a supplanter. Cf. Jacobite,
1. A familiar nickname of, or substitute for,
You are John Rugby, and you are Jack
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.
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 blasting.
(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 multiplying speed. (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
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. Shak.
Like an uninstructed bowler who thinks to attain the
jack by delivering his bowl straight forward upon
it. Sir W. Scott.
7. The male of certain animals, as of the
8. (Zoöl.) (a) A
young pike; a pickerel. (b) The
jurel. (c) A large, California rock fish
(Sebastodes paucispinus); -- called also boccaccio, and
mérou. (d) The wall-eyed
9. A drinking measure holding half a pint;
also, one holding a quarter of a pint. [Prov. Eng.]
10. (Naut.) (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. Dana, Jr.
11. The knave of a suit of playing
☞ 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, etc.
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 and spars. -- 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
(Zoöl.), the whimbrel. -- Jack
frame. (Cotton Spinning) See 4
(g), above. -- Jack Frost,
frost personified as a mischievous person. -- Jack
hare, a male hare. Cowper. -- Jack
lamp, a lamp for still hunting and camp use. See def. 4
(n.), above. -- 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. -- Jack rabbit
(Zoöl.), 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 (L.
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 (L. 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 (Zoöl.),
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 needles. -- Jack snipe.
(Zoöl.) 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 others.
-- 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 the gaff.
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. -- Jack-at-a-pinch.
(a) One called upon to take the place of another
in an emergency. (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 of
work. -- Jack-by-the-hedge (Bot.),
a plant of the genus Erysimum (E. 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-a-box. (a) (Bot.) A tropical
tree (Hernandia sonora), which bears a drupe that rattles when
dry in the inflated calyx. (b) A child's
toy, consisting of a box, out of which, when the lid is raised, a
figure springs. (c) (Mech.) An
epicyclic train of bevel gears for transmitting rotary motion to two
parts in such a manner that their relative rotation may be variable;
applied to driving the wheels of tricycles, road locomotives, and to
cotton machinery, etc.; an equation box; a jack frame; -- called also
compensating gearing. (d) A large
wooden screw turning in a nut attached to the crosspiece of a rude
press. -- Jack-in-office, an insolent
fellow in authority. Wolcott. -- Jack-in-the-
bush (Bot.), a tropical shrub with red fruit
(Cordia Cylindrostachya). -- Jack-in-the-
green, a chimney sweep inclosed in a framework of
boughs, carried in Mayday processions. -- Jack-in-the-
pulpit (Bot.), the American plant
Arisæma triphyllum, or Indian turnip, in which the
upright spadix is inclosed. -- 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 story. -- Jack-with-a-lantern,
Jack-o'-lantern. (a) An ignis
fatuus; a will-o'-the-wisp. "[Newspaper speculations] supplying
so many more jack-o'-lanterns to the future historian."
Lowell. (b) A lantern made of a pumpkin so
prepared as to show in illumination the features of a human face,
etc. -- Yellow Jack (Naut.), the
yellow fever; also, the quarantine flag. See Yellow flag,