The Collaborative International Dictionary of English v.0.48:

Horse \Horse\ (h[^o]rs), n. [AS. hors; akin to OS. hros, D. &
   OHG. ros, G. ross, Icel. hross; and perh. to L. currere to
   run, E. course, current Cf. Walrus.]
   1. (Zool.) A hoofed quadruped of the genus Equus;
      especially, the domestic horse (Equus caballus), which
      was domesticated in Egypt and Asia at a very early period.
      It has six broad molars, on each side of each jaw, with
      six incisors, and two canine teeth, both above and below.
      The mares usually have the canine teeth rudimentary or
      wanting. The horse differs from the true asses, in having
      a long, flowing mane, and the tail bushy to the base.
      Unlike the asses it has callosities, or chestnuts, on all
      its legs. The horse excels in strength, speed, docility,
      courage, and nobleness of character, and is used for
      drawing, carrying, bearing a rider, and like purposes.
      [1913 Webster]

   Note: Many varieties, differing in form, size, color, gait,
         speed, etc., are known, but all are believed to have
         been derived from the same original species. It is
         supposed to have been a native of the plains of Central
         Asia, but the wild species from which it was derived is
         not certainly known. The feral horses of America are
         domestic horses that have run wild; and it is probably
         true that most of those of Asia have a similar origin.
         Some of the true wild Asiatic horses do, however,
         approach the domestic horse in several characteristics.
         Several species of fossil (Equus) are known from the
         later Tertiary formations of Europe and America. The
         fossil species of other genera of the family
         Equid[ae] are also often called horses, in general
         sense.
         [1913 Webster]

   2. The male of the genus Equus, in distinction from the
      female or male; usually, a castrated male.
      [1913 Webster]

   3. Mounted soldiery; cavalry; -- used without the plural
      termination; as, a regiment of horse; -- distinguished
      from foot.
      [1913 Webster]

            The armies were appointed, consisting of twenty-five
            thousand horse and foot.              --Bacon.
      [1913 Webster]

   4. A frame with legs, used to support something; as, a
      clotheshorse, a sawhorse, etc.
      [1913 Webster]

   5. A frame of timber, shaped like a horse, on which soldiers
      were made to ride for punishment.
      [1913 Webster]

   6. Anything, actual or figurative, on which one rides as on a
      horse; a hobby.
      [1913 Webster]

   7. (Mining) A mass of earthy matter, or rock of the same
      character as the wall rock, occurring in the course of a
      vein, as of coal or ore; hence, to take horse -- said of a
      vein -- is to divide into branches for a distance.
      [1913 Webster]

   8. (Naut.)
      (a) See Footrope, a.
      (b) A breastband for a leadsman.
      (c) An iron bar for a sheet traveler to slide upon.
      (d) A jackstay. --W. C. Russell. --Totten.
          [1913 Webster]

   9. (Student Slang)
      (a) A translation or other illegitimate aid in study or
          examination; -- called also trot, pony, Dobbin.
      (b) Horseplay; tomfoolery.
          [Webster 1913 Suppl.]

   10. heroin. [slang]
       [PJC]

   11. horsepower. [Colloq. contraction]
       [PJC]

   Note: Horse is much used adjectively and in composition to
         signify of, or having to do with, a horse or horses,
         like a horse, etc.; as, horse collar, horse dealer or
         horse?dealer, horsehoe, horse jockey; and hence, often
         in the sense of strong, loud, coarse, etc.; as,
         horselaugh, horse nettle or horse-nettle, horseplay,
         horse ant, etc.
         [1913 Webster]

   Black horse, Blood horse, etc. See under Black, etc.

   Horse aloes, caballine aloes.

   Horse ant (Zool.), a large ant (Formica rufa); -- called
      also horse emmet.

   Horse artillery, that portion of the artillery in which the
      cannoneers are mounted, and which usually serves with the
      cavalry; flying artillery.

   Horse balm (Bot.), a strong-scented labiate plant
      (Collinsonia Canadensis), having large leaves and
      yellowish flowers.

   Horse bean (Bot.), a variety of the English or Windsor bean
      (Faba vulgaris), grown for feeding horses.

   Horse boat, a boat for conveying horses and cattle, or a
      boat propelled by horses.

   Horse bot. (Zool.) See Botfly, and Bots.

   Horse box, a railroad car for transporting valuable horses,
      as hunters. [Eng.]

   Horse breaker or Horse trainer, one employed in subduing
      or training horses for use.

   Horse car.
       (a) A railroad car drawn by horses. See under Car.
       (b) A car fitted for transporting horses.

   Horse cassia (Bot.), a leguminous plant (Cassia
      Javanica), bearing long pods, which contain a black,
      catharic pulp, much used in the East Indies as a horse
      medicine.

   Horse cloth, a cloth to cover a horse.

   Horse conch (Zool.), a large, spiral, marine shell of the
      genus Triton. See Triton.

   Horse courser.
       (a) One that runs horses, or keeps horses for racing.
           --Johnson.
       (b) A dealer in horses. [Obs.] --Wiseman.

   Horse crab (Zool.), the Limulus; -- called also
      horsefoot, horsehoe crab, and king crab.

   Horse crevall['e] (Zool.), the cavally.

   Horse emmet (Zool.), the horse ant.

   Horse finch (Zool.), the chaffinch. [Prov. Eng.]

   Horse gentian (Bot.), fever root.

   Horse iron (Naut.), a large calking iron.

   Horse latitudes, a space in the North Atlantic famous for
      calms and baffling winds, being between the westerly winds
      of higher latitudes and the trade winds. --Ham. Nav.
      Encyc.

   Horse mackrel. (Zool.)
       (a) The common tunny (Orcynus thunnus), found on the
           Atlantic coast of Europe and America, and in the
           Mediterranean.
       (b) The bluefish (Pomatomus saltatrix).
       (c) The scad.
       (d) The name is locally applied to various other fishes,
           as the California hake, the black candlefish, the
           jurel, the bluefish, etc.

   Horse marine (Naut.), an awkward, lubbery person; one of a
      mythical body of marine cavalry. [Slang]

   Horse mussel (Zool.), a large, marine mussel (Modiola
      modiolus), found on the northern shores of Europe and
      America.

   Horse nettle (Bot.), a coarse, prickly, American herb, the
      Solanum Carolinense.

   Horse parsley. (Bot.) See Alexanders.

   Horse purslain (Bot.), a coarse fleshy weed of tropical
      America (Trianthema monogymnum).

   Horse race, a race by horses; a match of horses in running
      or trotting.

   Horse racing, the practice of racing with horses.

   Horse railroad, a railroad on which the cars are drawn by
      horses; -- in England, and sometimes in the United States,
      called a tramway.

   Horse run (Civil Engin.), a device for drawing loaded
      wheelbarrows up an inclined plane by horse power.

   Horse sense, strong common sense. [Colloq. U.S.]

   Horse soldier, a cavalryman.

   Horse sponge (Zool.), a large, coarse, commercial sponge
      (Spongia equina).

   Horse stinger (Zool.), a large dragon fly. [Prov. Eng.]

   Horse sugar (Bot.), a shrub of the southern part of the
      United States (Symplocos tinctoria), whose leaves are
      sweet, and good for fodder.

   Horse tick (Zool.), a winged, dipterous insect (Hippobosca
      equina), which troubles horses by biting them, and
      sucking their blood; -- called also horsefly, horse
      louse, and forest fly.

   Horse vetch (Bot.), a plant of the genus Hippocrepis
      (Hippocrepis comosa), cultivated for the beauty of its
      flowers; -- called also horsehoe vetch, from the
      peculiar shape of its pods.

   Iron horse, a locomotive. [Colloq.]

   Salt horse, the sailor's name for salt beef.

   To look a gift horse in the mouth, to examine the mouth of
      a horse which has been received as a gift, in order to
      ascertain his age; -- hence, to accept favors in a
      critical and thankless spirit. --Lowell.

   To take horse.
       (a) To set out on horseback. --Macaulay.
       (b) To be covered, as a mare.
       (c) See definition 7 (above).
           [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

King \King\, n. [AS. cyng, cyning; akin to OS. kuning, D.
   koning, OHG. kuning, G. k["o]nig, Icel. konungr, Sw. konung,
   Dan. konge; formed with a patronymic ending, and fr. the root
   of E. kin; cf. Icel. konr a man of noble birth. [root]44. See
   Kin.]
   1. A chief ruler; a sovereign; one invested with supreme
      authority over a nation, country, or tribe, usually by
      hereditary succession; a monarch; a prince. "Ay, every
      inch a king." --Shak.
      [1913 Webster]

            Kings will be tyrants from policy, when subjects are
            rebels from principle.                --Burke.
      [1913 Webster]

            There was a State without king or nobles. --R.
                                                  Choate.
      [1913 Webster]

            But yonder comes the powerful King of Day,
            Rejoicing in the east                 --Thomson.
      [1913 Webster]

   2. One who, or that which, holds a supreme position or rank;
      a chief among competitors; as, a railroad king; a money
      king; the king of the lobby; the king of beasts.
      [1913 Webster]

   3. A playing card having the picture of a king[1]; as, the
      king of diamonds.
      [1913 Webster]

   4. The chief piece in the game of chess.
      [1913 Webster]

   5. A crowned man in the game of draughts.
      [1913 Webster]

   6. pl. The title of two historical books in the Old
      Testament.
      [1913 Webster]

   Note: King is often used adjectively, or in combination, to
         denote pre["e]minence or superiority in some
         particular; as, kingbird; king crow; king vulture.
         [1913 Webster]

   Apostolic king. See Apostolic.

   King-at-arms, or King-of-arms, the chief heraldic officer
      of a country. In England the king-at-arms was formerly of
      great authority. His business is to direct the heralds,
      preside at their chapters, and have the jurisdiction of
      armory. There are three principal kings-at-arms, viz.,
      Garter, Clarencieux, and Norroy. The latter (literally
      north roy or north king) officiates north of the Trent.

   King auk (Zool.), the little auk or sea dove.

   King bird of paradise. (Zool.), See Bird of paradise.

   King card, in whist, the best unplayed card of each suit;
      thus, if the ace and king of a suit have been played, the
      queen is the king card of the suit.

   King Cole, a legendary king of Britain, who is said to have
      reigned in the third century.

   King conch (Zool.), a large and handsome univalve shell
      (Cassis cameo), found in the West Indies. It is used for
      making cameos. See Helmet shell, under Helmet.

   King Cotton, a popular personification of the great staple
      production of the southern United States.

   King crab. (Zool.)
      (a) The limulus or horseshoe crab. See Limulus.
      (b) The large European spider crab or thornback (Maia
          squinado).
      (c) A large crab of the northern Pacific (Paralithodes
          camtshatica), especially abundant on the coasts of
          Alaska and Japan, and popular as a food; called also
          Alaskan king crab.

   King crow. (Zool.)
      (a) A black drongo shrike (Buchanga atra) of India; --
          so called because, while breeding, they attack and
          drive away hawks, crows, and other large birds.
      (b) The Dicrurus macrocercus of India, a crested bird
          with a long, forked tail. Its color is black, with
          green and blue reflections. Called also devil bird.


   King duck (Zool.), a large and handsome eider duck
      (Somateria spectabilis), inhabiting the arctic regions
      of both continents.

   King eagle (Zool.), an eagle (Aquila heliaca) found in
      Asia and Southeastern Europe. It is about as large as the
      golden eagle. Some writers believe it to be the imperial
      eagle of Rome.

   King hake (Zool.), an American hake (Phycis regius),
      found in deep water along the Atlantic coast.

   King monkey (Zool.), an African monkey (Colobus
      polycomus), inhabiting Sierra Leone.

   King mullet (Zool.), a West Indian red mullet (Upeneus
      maculatus); -- so called on account of its great beauty.
      Called also goldfish.

   King of terrors, death.

   King parrakeet (Zool.), a handsome Australian parrakeet
      (Platycercys scapulatus), often kept in a cage. Its
      prevailing color is bright red, with the back and wings
      bright green, the rump blue, and tail black.

   King penguin (Zool.), any large species of penguin of the
      genus Aptenodytes; esp., Aptenodytes longirostris, of
      the Falkland Islands and Kerguelen Land, and Aptenodytes
      Patagonica, of Patagonia.

   King rail (Zool.), a small American rail (Rallus
      elegans), living in fresh-water marshes. The upper parts
      are fulvous brown, striped with black; the breast is deep
      cinnamon color.

   King salmon (Zool.), the quinnat. See Quinnat.

   King's counsel, or Queen's counsel (Eng. Law), barristers
      learned in the law, who have been called within the bar,
      and selected to be the king's or queen's counsel. They
      answer in some measure to the advocates of the revenue
      (advocati fisci) among the Romans. They can not be
      employed against the crown without special license.
      --Wharton's Law Dict.

   King's cushion, a temporary seat made by two persons
      crossing their hands. [Prov. Eng.] --Halliwell.

   The king's English, correct or current language of good
      speakers; pure English. --Shak.

   King's evidence or Queen's evidence, testimony in favor
      of the Crown by a witness who confesses his guilt as an
      accomplice. See under Evidence. [Eng.]

   King's evil, scrofula; -- so called because formerly
      supposed to be healed by the touch of a king.

   King snake (Zool.), a large, nearly black, harmless snake
      (Ophiobolus getulus) of the Southern United States; --
      so called because it kills and eats other kinds of snakes,
      including even the rattlesnake.

   King's spear (Bot.), the white asphodel (Asphodelus
      albus).

   King's yellow, a yellow pigment, consisting essentially of
      sulphide and oxide of arsenic; -- called also yellow
      orpiment.

   King tody (Zool.), a small fly-catching bird (Eurylaimus
      serilophus) of tropical America. The head is adorned with
      a large, spreading, fan-shaped crest, which is bright red,
      edged with black.

   King vulture (Zool.), a large species of vulture
      (Sarcorhamphus papa), ranging from Mexico to Paraguay,
      The general color is white. The wings and tail are black,
      and the naked carunculated head and the neck are
      briliantly colored with scarlet, yellow, orange, and blue.
      So called because it drives away other vultures while
      feeding.

   King wood, a wood from Brazil, called also violet wood,
      beautifully streaked in violet tints, used in turning and
      small cabinetwork. The tree is probably a species of
      Dalbergia. See Jacaranda.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Limulus \Lim"u*lus\ (l[i^]m"[-u]*l[u^]s), n.; pl. Limuli
   (-l[imac]). [L., dim. of limus sidelong, askance.] (Zool.)
   The only existing genus of Merostomata. It includes only a
   few species from the East Indies, and one (Limulus
   polyphemus) from the Atlantic coast of North America. Called
   also Molucca crab, king crab, horseshoe crab, and
   horsefoot.
   [1913 Webster]

WordNet (r) 3.0 (2006):

king crab
    n 1: meat of large cold-water crab; mainly leg meat [syn:
         Alaska king crab, Alaskan king crab, king crab,
         Alaska crab]
    2: a large spider crab of Europe [syn: European spider crab,
       king crab, Maja squinado]
    3: large edible crab of northern Pacific waters especially along
       the coasts of Alaska and Japan [syn: king crab, Alaska
       crab, Alaskan king crab, Alaska king crab, Paralithodes
       camtschatica]
    4: large marine arthropod of the Atlantic coast of North America
       having a domed carapace that is shaped like a horseshoe and a
       stiff pointed tail; a living fossil related to the wood louse
       [syn: horseshoe crab, king crab, Limulus polyphemus,
       Xiphosurus polyphemus]