What is "blue jacket"

Jacket \Jack"et\, n. [F. jaquette, dim. of jaque. See 3d Jack, n.]

1. A short upper garment, extending downward to the hips; a short coat without skirts.

2. An outer covering for anything, esp. a covering of some nonconducting material such as wood or felt, used to prevent radiation of heat, as from a steam boiler, cylinder, pipe, etc.

3. (Mil.) In ordnance, a strengthening band surrounding and re["e]nforcing the tube in which the charge is fired.

4. A garment resembling a waistcoat lined with cork, to serve as a life preserver; -- called also cork jacket.

   Blue jacket. (Naut.) See under Blue.

   Steam jacket, a space filled with steam between an inner and an outer cylinder, or between a casing and a receptacle, as a kettle.

   To dust one's jacket, to give one a beating. [Colloq.]

Blue \Blue\ (bl[=u]), a. [Compar. Bluer (bl[=u]"[~e]r); superl. Bluest.] [OE. bla, blo, blew, blue, livid, black, fr. Icel.bl[=a]r livid; akin to Dan. blaa blue, Sw. bl[*a], D. blauw, OHG. bl[=a]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]us); 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 Blue mould, the blue fungus ( Aspergillus glaucus) which grows on cheese. --Brande & C. Blue Monday,

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

   2. a Monday considered as depressing because it is a workday in contrast to the relaxation of the weekend. 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.)

      1. A pill of prepared mercury, used as an aperient, etc.

      2. Blue mass. Blue ribbon.

         1. The ribbon worn by members of the order of the Garter; -- hence, a member of that order.

         2. 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.

   3. 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.

      Big Blue, the International Business Machines corporation. [Wall Street slang.] PJC

      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.

      For his religion . . . 'T was Presbyterian, true blue.
      --Hudibras.

Blue Jacket or Weyapiersenwah (c. 1743 – 1810) was a war chief of the Shawnee people, known for his militant defense of Shawnee lands in the Ohio Country. Perhaps the pre-eminent American Indian leader in the Northwest Indian War, in which a pantribal confederacy fought several battles with the nascent United States, he was an important predecessor of the famous Shawnee leader Tecumseh.