jack \jack\ ja^k, n. f. jacques james, l. jacobus, gr. ?,
   heb. ya 'aq=ob jacob; prop., seizing by the heel; hence, a
   supplanter. cf. jacobite, jockey.
   1913 webster
   1. a familiar nickname of, or substitute for, john.
      1913 webster

            you are john rugby, and you are jack rugby. --shak.
      1913 webster

   2. an impertinent or silly fellow; a simpleton; a boor; a
      clown; also, a servant; a rustic. "jack fool." --chaucer.
      1913 webster

            since every jack became a gentleman,
            there 's many a gentle person made a jack. --shak.
      1913 webster

   3. a popular colloquial name for a sailor; -- called also
      jack tar, and jack afloat.
      1913 webster

   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.
          1913 webster

   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.
      1913 webster

   6. the small bowl used as a mark in the game of bowls.
      --shak.
      1913 webster

            like an uninstructed bowler who thinks to attain the
            jack by delivering his bowl straight forward upon
            it.                                   --sir w.
                                                  scott.
      1913 webster

   7. the male of certain animals, as of the ass.
      1913 webster

   8. zool.
      a a young pike; a pickerel.
      b the jurel.
      c a large, california rock fish sebastodes
          paucispinus; -- called also boccaccio, and
          m'erou.
      d the wall-eyed pike.
          1913 webster

   9. a drinking measure holding half a pint; also, one holding
      a quarter of a pint. prov. eng. --halliwell.
      1913 webster

   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.
           1913 webster

   11. the knave of a suit of playing cards.

   12. pl. a game played with small metallic, with
       tetrahedrally oriented spikes objects the jacks1950+,
       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
       jackstones.
       pjc

   13. money. slang
       pjc

   14. apple jack.
       pjc

   15. brandy.
       pjc

   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,
         etc.
         1913 webster

   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 zool., the whimbrel.

   jack frame. cotton spinning see 4
       g, above.

   jack frost, frost or cold weather 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. see also
      jackpot.

   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
      needles.

   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
      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.
      1913 webster

   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
      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
      cordia cylindrostachya.

   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
      story.

   yellow jack naut., the yellow fever; also, the quarantine
      flag. see yellow flag, under flag.
      1913 webster
see also:
jacobite jockey jack tar jack afloat hopper sebastodes paucispinus 
boccaccio m'erou union jack jack crosstree jackstones 
jack arch jack back back jack block jack boots 
jack crosstree jack curlew jack frame jack frost jack hare 
jack lamp jack plane jack post jack pot jackpot 
jack rabbit lepus californicus lepus callotis lepus campestris jack rafter 
jack salmon jack sauce jack shaft jack sinker jack snipe 
jack staff jack timber jack towel jack truss jack tree 
jack jack yard blue jack hydraulic jack jack-at-a-pinch 
jack-at-all-trades jack-by-the-hedge erysimum erysimum alliaria alliaria officinalis 
sauce-alone jack-in-office jack-in-the-bush cordia cylindrostachya jack-in-the-green 
jack-of-the-buttery sedum acre jack-of-the-clock jack-on-both-sides jack-out-of-office 
jack the giant killer yellow jack yellow flag flag