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]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 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: Webster's Revised Unabridged Dictionary (1913)