1. [n]  a member of the genus Canis (probably descended from the common wolf) that has been domesticated by man since prehistoric times; occurs in many breeds; "the dog barked all night"
2. [n]  metal supports for logs in a fireplace; "the andirons were too hot to touch"
3. [n]  a hinged catch that fits into a notch of a ratchet to move a wheel forward or prevent it from moving backward
4. [n]  someone who is morally reprehensible; "you dirty dog"
5. [n]  informal term for a man; "you lucky dog"
6. [n]  a dull unattractive unpleasant girl or woman; "she got a reputation as a frump"; "she's a real dog"
7. [v]  go after with the intent to catch

Dog
Photographs of over 300 works of art and supporting text celebrate the canine in art and literature, including chapters on sporting dogs, companion dogs, wild dogs, working dogs, dogs at rest, and symbolic dogs.

more details ...

1. \Dog\ (d[o^]g), n. [AS. docga; akin to D. dog mastiff, Dan.
   dogge, Sw. dogg.]
   1. (Zo["o]l.) A quadruped of the genus {Canis}, esp. the
      domestic dog ({C. familiaris}).
   Note: The dog is distinguished above all others of the
         inferior animals for intelligence, docility, and
         attachment to man. There are numerous carefully bred
         varieties, as the beagle, bloodhound, bulldog,
         coachdog, collie, Danish dog, foxhound, greyhound,
         mastiff, pointer, poodle, St. Bernard, setter, spaniel,
         spitz dog, terrier, etc. There are also many mixed
         breeds, and partially domesticated varieties, as well
         as wild dogs, like the dingo and dhole. (See these
         names in the Vocabulary.)
   2. A mean, worthless fellow; a wretch.
            What is thy servant, which is but a dog, that he
            should do this great thing?           -- 2 Kings
                                                  viii. 13 (Rev.
                                                  Ver. )
   3. A fellow; -- used humorously or contemptuously; as, a sly
      dog; a lazy dog. [Colloq.]
   4. (Astron.) One of the two constellations, Canis Major and
      Canis Minor, or the Greater Dog and the Lesser Dog. Canis
      Major contains the Dog Star (Sirius).
   5. An iron for holding wood in a fireplace; a firedog; an
      andiron.
   6. (Mech.)
      (a) A grappling iron, with a claw or claws, for fastening
          into wood or other heavy articles, for the purpose of
          raising or moving them.
      (b) An iron with fangs fastening a log in a saw pit, or on
          the carriage of a sawmill.
      (c) A piece in machinery acting as a catch or clutch;
          especially, the carrier of a lathe, also, an
          adjustable stop to change motion, as in a machine
          tool.
   Note: Dog is used adjectively or in composition, commonly in
         the sense of relating to, or characteristic of, a dog.
         It is also used to denote a male; as, dog fox or g-fox,
         a male fox; dog otter or dog-otter, dog wolf, etc.; --
         also to denote a thing of cheap or mean quality; as,
         dog Latin.
   {A dead dog}, a thing of no use or value. --1 Sam. xxiv. 14.
   {A dog in the manger}, an ugly-natured person who prevents
      others from enjoying what would be an advantage to them
      but is none to him.
   {Dog ape} (Zo["o]l.), a male ape.
   {Dog cabbage}, or {Dog's cabbage} (Bot.), a succulent herb,
      native to the Mediterranean region ({Thelygonum
      Cynocrambe}).
   {Dog cheap}, very cheap. See under {Cheap}.
   {Dog ear} (Arch.), an acroterium. [Colloq.]
   {Dog flea} (Zo["o]l.), a species of flea ({Pulex canis})
      which infests dogs and cats, and is often troublesome to
      man. In America it is the common flea. See {Flea}, and
      {Aphaniptera}.
   {Dog grass} (Bot.), a grass ({Triticum caninum}) of the same
      genus as wheat.
   {Dog Latin}, barbarous Latin; as, the dog Latin of pharmacy.
   {Dog lichen} (Bot.), a kind of lichen ({Peltigera canina})
      growing on earth, rocks, and tree trunks, -- a lobed
      expansion, dingy green above and whitish with fuscous
      veins beneath.
   {Dog louse} (Zo["o]l.), a louse that infests the dog, esp.
      {H[ae]matopinus piliferus}; another species is
      {Trichodectes latus}.
   {Dog power}, a machine operated by the weight of a dog
      traveling in a drum, or on an endless track, as for
      churning.
   {Dog salmon} (Zo["o]l.), a salmon of northwest America and
      northern Asia; -- the {gorbuscha}; -- called also {holia},
      and {hone}.
   {Dog shark}. (Zo["o]l.) See {Dogfish}.
   {Dog's meat}, meat fit only for dogs; refuse; offal.
   {Dog Star}. See in the Vocabulary.
   {Dog wheat} (Bot.), Dog grass.
   {Dog whelk} (Zo["o]l.), any species of univalve shells of the
      family {Nassid[ae]}, esp. the {Nassa reticulata} of
      England.
   {To give, or throw}, {to the dogs}, to throw away as useless.
      ``Throw physic to the dogs; I'll none of it.'' --Shak.
   {To go to the dogs}, to go to ruin; to be ruined.
   

2. \Dog\, v. t. [imp. & p. p. {Dogged}; p. pr. & vb. n.
   {Dogging}.]
   To hunt or track like a hound; to follow insidiously or
   indefatigably; to chase with a dog or dogs; to worry, as if
   by dogs; to hound with importunity.
         I have been pursued, dogged, and waylaid. -- Pope.
         Your sins will dog you, pursue you.      --Burroughs.
         Eager ill-bred petitioners, who do not so properly
         supplicate as hunt the person whom they address to,
         dogging him from place to place, till they even extort
         an answer to their rude requests.        -- South.
   

frequently mentioned both in the Old and New Testaments. Dogs were used by the Hebrews as a watch for their houses (Isa. 56:10), and for guarding their flocks (Job 30:1). There were also then as now troops of semi-wild dogs that wandered about devouring dead bodies and the offal of the streets (1 Kings 14:11; 16:4; 21:19, 23; 22:38; Ps. 59:6, 14).

As the dog was an unclean animal, the terms "dog," "dog's head," "dead dog," were used as terms of reproach or of humiliation (1 Sam. 24:14; 2 Sam. 3:8; 9:8; 16:9). Paul calls false apostles "dogs" (Phil. 3:2). Those who are shut out of the kingdom of heaven are also so designated (Rev. 22:15). Persecutors are called "dogs" (Ps. 22:16). Hazael's words, "Thy servant which is but a dog" (2 Kings 8:13), are spoken in mock humility=impossible that one so contemptible as he should attain to such power.