The Collaborative International Dictionary of English v.0.48:

Devil \Dev"il\, n. [AS. de['o]fol, de['o]ful; akin to G. ?eufel,
   Goth. diaba['u]lus; all fr. L. diabolus the devil, Gr. ? the
   devil, the slanderer, fr. ? to slander, calumniate, orig., to
   throw across; ? across + ? to throw, let fall, fall; cf. Skr.
   gal to fall. Cf. Diabolic.]
   1. The Evil One; Satan, represented as the tempter and
      spiritual of mankind.
      [1913 Webster]

            [Jesus] being forty days tempted of the devil.
                                                  --Luke iv. 2.
      [1913 Webster]

            That old serpent, called the Devil, and Satan, which
            deceiveth the whole world.            --Rev. xii. 9.
      [1913 Webster]

   2. An evil spirit; a demon.
      [1913 Webster]

            A dumb man possessed with a devil.    --Matt. ix.
                                                  32.
      [1913 Webster]

   3. A very wicked person; hence, any great evil. "That devil
      Glendower." "The devil drunkenness." --Shak.
      [1913 Webster]

            Have not I chosen you twelve, and one of you is a
            devil?                                --John vi. 70.
      [1913 Webster]

   4. An expletive of surprise, vexation, or emphasis, or,
      ironically, of negation. [Low]
      [1913 Webster]

            The devil a puritan that he is, . . . but a
            timepleaser.                          --Shak.
      [1913 Webster]

            The things, we know, are neither rich nor rare,
            But wonder how the devil they got there. --Pope.
      [1913 Webster]

   5. (Cookery) A dish, as a bone with the meat, broiled and
      excessively peppered; a grill with Cayenne pepper.
      [1913 Webster]

            Men and women busy in baking, broiling, roasting
            oysters, and preparing devils on the gridiron. --Sir
                                                  W. Scott.
      [1913 Webster]

   6. (Manuf.) A machine for tearing or cutting rags, cotton,
      etc.
      [1913 Webster]

   Blue devils. See under Blue.

   Cartesian devil. See under Cartesian.

   Devil bird (Zool.), one of two or more South African drongo
      shrikes (Edolius retifer, and Edolius remifer),
      believed by the natives to be connected with sorcery.

   Devil may care, reckless, defiant of authority; -- used
      adjectively. --Longfellow.

   Devil's apron (Bot.), the large kelp (Laminaria
      saccharina, and Laminaria longicruris) of the Atlantic
      ocean, having a blackish, leathery expansion, shaped
      somewhat like an apron.

   Devil's coachhorse. (Zool.)
      (a) The black rove beetle (Ocypus olens). [Eng.]
      (b) A large, predacious, hemipterous insect (Prionotus
          cristatus); the wheel bug. [U.S.]

   Devil's darning-needle. (Zool.) See under Darn, v. t.

   Devil's fingers, Devil's hand (Zool.), the common British
      starfish (Asterias rubens); -- also applied to a sponge
      with stout branches. [Prov. Eng., Irish & Scot.]

   Devil's riding-horse (Zool.), the American mantis (Mantis
      Carolina).

   The Devil's tattoo, a drumming with the fingers or feet.
      "Jack played the Devil's tattoo on the door with his boot
      heels." --F. Hardman (Blackw. Mag.).

   Devil worship, worship of the power of evil; -- still
      practiced by barbarians who believe that the good and evil
      forces of nature are of equal power.

   Printer's devil, the youngest apprentice in a printing
      office, who runs on errands, does dirty work (as washing
      the ink rollers and sweeping), etc. "Without fearing the
      printer's devil or the sheriff's officer." --Macaulay.

   Tasmanian devil (Zool.), a very savage carnivorous
      marsupial of Tasmania (Dasyurus ursinus syn. Diabolus
      ursinus).

   To play devil with, to molest extremely; to ruin. [Low]
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

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.
      [1913 Webster]

   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.
      [1913 Webster]

   3. Low in spirits; melancholy; as, to feel blue.
      [1913 Webster]

   4. Suited to produce low spirits; gloomy in prospect; as,
      thongs looked blue. [Colloq.]
      [1913 Webster]

   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.
      [1913 Webster]

   6. Literary; -- applied to women; -- an abbreviation of
      bluestocking. [Colloq.]
      [1913 Webster]

            The ladies were very blue and well informed.
                                                  --Thackeray.
      [1913 Webster]

   Blue asbestus. See Crocidolite.

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

   Blue blood. See under Blood.

   Blue buck (Zool.), a small South African antelope
      (Cephalophus pygm[ae]us); also applied to a larger
      species ([AE]goceras leucoph[ae]us); the blaubok.

   Blue cod (Zool.), the buffalo cod.

   Blue crab (Zool.), 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,
      (a) a Monday following a Sunday of dissipation, or itself
          given to dissipation (as the Monday before Lent).
      (b) 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.)
      (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 (Zool.), 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.
      [1913 Webster]

            For his religion . . .
            'T was Presbyterian, true blue.       --Hudibras.
      [1913 Webster]

WordNet (r) 3.0 (2006):

blue devils
    n 1: a state of depression; "he had a bad case of the blues"
         [syn: blues, blue devils, megrims, vapors,
         vapours]

Moby Thesaurus II by Grady Ward, 1.0:

26 Moby Thesaurus words for "blue devils":
   blahs, blue Johnnies, blues, dismals, dods, doldrums, dolefuls,
   dorts, dumps, frumps, grumps, megrims, mopes, mulligrubs, mumps,
   pink elephants, pink spiders, pouts, snakes, sulks, sullens,
   the beezie-weezies, the heebie-jeebies, the jimjams,
   the screaming meemies, the shakes