Source : Webster's Revised Unabridged Dictionary (1913)

   {Jack rabbit} (Zo["o]l.), 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} (Zo["o]l.), 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}. (Zo["o]l.) 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 {Aris[ae]ma
      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}.

Blue \Blue\, a. [Compar. {Bluer}; superl. {Bluest}.] [OE. bla,
   blo, blew, blue, Sw. bl?, D. blauw, OHG. bl?o, G. blau; but
   influenced in form by F. bleu, from OHG. bl[=a]o.]
   1. Having the color of the clear sky, or a hue resembling it,
      whether lighter or darker; as, the deep, blue sea; as blue
      as a sapphire; blue violets. ``The blue firmament.''
      --Milton.

   2. Pale, without redness or glare, -- said of a flame; hence,
      of the color of burning brimstone, betokening the presence
      of ghosts or devils; as, the candle burns blue; the air
      was blue with oaths.

   3. Low in spirits; melancholy; as, to feel blue.

   4. Suited to produce low spirits; gloomy in prospect; as,
      thongs looked blue. [Colloq.]

   5. Severe or over strict in morals; gloom; as, blue and sour
      religionists; suiting one who is over strict in morals;
      inculcating an impracticable, severe, or gloomy mortality;
      as, blue laws.

   6. Literary; -- applied to women; -- an abbreviation of
      bluestocking. [Colloq.]

            The ladies were very blue and well informed.
                                                  --Thackeray.

   {Blue asbestus}. See {Crocidolite}.

   {Blue black}, of, or having, a very dark blue color, almost
      black.

   {Blue blood}. See under {Blood}.

   {Blue buck} (Zo["o]l.), a small South African antelope
      ({Cephalophus pygm[ae]us}); also applied to a larger
      species ({[AE]goceras leucoph[ae]u}s); the blaubok.

   {Blue cod} (Zo["o]l.), the buffalo cod.

   {Blue crab} (Zo["o]l.), the common edible crab of the
      Atlantic coast of the United States ({Callinectes
      hastatus}).

   {Blue curls} (Bot.), a common plant ({Trichostema
      dichotomum}), resembling pennyroyal, and hence called also
      {bastard pennyroyal}.

   {Blue devils}, apparitions supposed to be seen by persons
      suffering with {delirium tremens}; hence, very low
      spirits. ``Can Gumbo shut the hall door upon blue devils,
      or lay them all in a red sea of claret?'' --Thackeray.

   {Blue gage}. See under {Gage}, a plum.

   {Blue gum}, an Australian myrtaceous tree ({Eucalyptus
      globulus}), of the loftiest proportions, now cultivated in
      tropical and warm temperate regions for its timber, and as
      a protection against malaria. The essential oil is
      beginning to be used in medicine. The timber is very
      useful. See {Eucalyptus}.

   {Blue jack}, {Blue stone}, blue vitriol; sulphate of copper.
      

   {Blue jacket}, a man-of war's man; a sailor wearing a naval
      uniform.

   {Blue jaundice}. See under {Jaundice}.

   {Blue laws}, a name first used in the eighteenth century to
      describe certain supposititious laws of extreme rigor
      reported to have been enacted in New Haven; hence, any
      puritanical laws. [U. S.]

   {Blue light}, a composition which burns with a brilliant blue
      flame; -- used in pyrotechnics and as a night signal at
      sea, and in military operations.

   {Blue mantle} (Her.), one of the four pursuivants of the
      English college of arms; -- so called from the color of
      his official robes.

   {Blue mass}, a preparation of mercury from which is formed
      the blue pill. --McElrath.

   {Blue mold}, or mould, the blue fungus ({Aspergillus
      glaucus}) which grows on cheese. --Brande & C.

   {Blue Monday}, a Monday following a Sunday of dissipation, or
      itself given to dissipation (as the Monday before Lent).
      

   {Blue ointment} (Med.), mercurial ointment.

   {Blue Peter} (British Marine), a blue flag with a white
      square in the center, used as a signal for sailing, to
      recall boats, etc. It is a corruption of blue repeater,
      one of the British signal flags.

   {Blue pill}. (Med.)
      (a) A pill of prepared mercury, used as an aperient, etc.
      (b) Blue mass.

   {Blue ribbon}.
      (a) The ribbon worn by members of the order of the Garter;
          -- hence, a member of that order.
      (b) Anything the attainment of which is an object of great
          ambition; a distinction; a prize. ``These
          [scholarships] were the --blue ribbon of the
          college.'' --Farrar.
      (c) The distinctive badge of certain temperance or total
          abstinence organizations, as of the --Blue ribbon
          Army.

   {Blue ruin}, utter ruin; also, gin. [Eng. Slang] --Carlyle.

   {Blue spar} (Min.), azure spar; lazulite. See {Lazulite}.

   {Blue thrush} (Zo["o]l.), a European and Asiatic thrush
      ({Petrocossyphus cyaneas}).

   {Blue verditer}. See {Verditer}.

   {Blue vitriol} (Chem.), sulphate of copper, a violet blue
      crystallized salt, used in electric batteries, calico
      printing, etc.

   {Blue water}, the open ocean.

   {To look blue}, to look disheartened or dejected.

   {True blue}, genuine and thorough; not modified, nor mixed;
      not spurious; specifically, of uncompromising
      Presbyterianism, blue being the color adopted by the
      Covenanters.

Source : WordNet®

blue jack
     n : small salmon of northern Pacific coasts and the Great Lakes
         [syn: {coho}, {cohoe}, {coho salmon}, {silver salmon}, {Onchorynchus
         kisutch}]