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, under Flag.
Jack (?), n. [F. jaque, jacque, perh. from the proper name Jacques. Cf.
Jacquerie.] A coarse and cheap mediæval coat of defense, esp. one made
of leather.
Their horsemen are with jacks for most part clad.
Sir J. Harrington.
Jack (?), n. [Named from its resemblance to a jack boot.] A pitcher or
can of waxed leather; -- called also black jack. [Obs.] Dryden.
Jack, v. i. To hunt game at night by means of a jack. See 2d Jack, n.,
4, n.
Jack, v. t. To move or lift, as a house, by means of a jack or jacks.
See 2d Jack, n., 5.
Jack`-a-dan"dy (?), n. A little dandy; a little, foppish, impertinent
fellow.
Jack"al` (?), n. [Pers. shaghl: cf. OF. jackal, F. chacal; cf. Skr.
çr.gla.]
1. (Zoöl.) Any one of several species of carnivorous animals inhabiting
Africa and Asia, related to the dog and wolf. They are cowardly,
nocturnal, and gregarious. They feed largely on carrion, and are noted
for their piercing and dismal howling.
The common species of Southern Asia (Canis aureus) is yellowish gray,
varied with brown on the shoulders, haunches, and legs. The common
African species (C. anthus) is darker in color.
2. One who does mean work for another's advantage, as jackals were once
thought to kill game which lions appropriated. [Colloq.] Ld. Lytton.
Jack"-a-lent (?), n. A small stuffed puppet to be pelted in Lent;
hence, a simple fellow.
Jack"a*napes (?), n. [For Jack o' (= of) apes; prop., a man who
exhibits apes.] [Written also jackanape.]