The Collaborative International Dictionary of English v.0.48:

Knight \Knight\, n. [OE. knight, cniht, knight, soldier, AS.
   cniht, cneoht, a boy, youth, attendant, military follower;
   akin to D. & G. knecht servant; perh. akin to E. kin.]
   1. A young servant or follower; a military attendant. [Obs.]
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   2.
      (a) In feudal times, a man-at-arms serving on horseback
          and admitted to a certain military rank with special
          ceremonies, including an oath to protect the
          distressed, maintain the right, and live a stainless
          life.
      (b) One on whom knighthood, a dignity next below that of
          baronet, is conferred by the sovereign, entitling him
          to be addressed as Sir; as, Sir John. [Eng.] Hence:
      (c) A champion; a partisan; a lover. "Give this ring to my
          true knight." Shak "In all your quarrels will I be
          your knight." --Tennyson.
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                Knights, by their oaths, should right poor
                ladies' harms.                    --Shak.
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   Note: Formerly, when a knight's name was not known, it was
         customary to address him as Sir Knight. The rank of a
         knight is not hereditary.
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   3. A piece used in the game of chess, usually bearing a
      horse's head.
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   4. A playing card bearing the figure of a knight; the knave
      or jack. [Obs.]
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   Carpet knight. See under Carpet.

   Knight of industry. See Chevalier d'industrie, under
      Chevalier.

   Knight of Malta, Knight of Rhodes, Knight of St. John of
   Jerusalem. See Hospitaler.

   Knight of the post, one who gained his living by giving
      false evidence on trials, or false bail; hence, a sharper
      in general. --Nares. "A knight of the post, . . . quoth
      he, for so I am termed; a fellow that will swear you
      anything for twelve pence." --Nash.

   Knight of the shire, in England, one of the representatives
      of a county in Parliament, in distinction from the
      representatives of cities and boroughs.

   Knights commanders, Knights grand cross, different
      classes of the Order of the Bath. See under Bath, and
      Companion.

   Knights of labor, a secret organization whose professed
      purpose is to secure and maintain the rights of workingmen
      as respects their relations to their employers. [U. S.]

   Knights of Pythias, a secret order, founded in Washington,
      D. C., in 1864, for social and charitable purposes.

   Knights of the Round Table, knights belonging to an order
      which, according to the legendary accounts, was instituted
      by the mythical King Arthur. They derived their common
      title from the table around which they sat on certain
      solemn days. --Brande & C.
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The Collaborative International Dictionary of English v.0.48:

Carpet \Car"pet\ (k[aum]r"p[e^]t), n. [OF. carpite rug, soft of
   cloth, F. carpette coarse packing cloth, rug (cf. It. carpita
   rug, blanket), LL. carpeta, carpita, woolly cloths, fr. L.
   carpere to pluck, to card (wool); cf. Gr. karpo`s fruit, E.
   Harvest.]
   1. A heavy woven or felted fabric, usually of wool, but also
      of cotton, hemp, straw, etc.; esp. a floor covering made
      in breadths to be sewed together and nailed to the floor,
      as distinguished from a rug or mat; originally, also, a
      wrought cover for tables.
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            Tables and beds covered with copes instead of
            carpets and coverlets.                --T. Fuller.
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   2. A smooth soft covering resembling or suggesting a carpet.
      "The grassy carpet of this plain." --Shak.
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   Carpet beetle or Carpet bug (Zool.), a small beetle
      (Anthrenus scrophulari[ae]), which, in the larval state,
      does great damage to carpets and other woolen goods; --
      also called buffalo bug.

   Carpet knight.
      (a) A knight who enjoys ease and security, or luxury, and
          has not known the hardships of the field; a hero of
          the drawing room; an effeminate person. --Shak.
      (b) One made a knight, for some other than military
          distinction or service.

   Carpet moth (Zool.), the larva of an insect which feeds on
      carpets and other woolen goods. There are several kinds.
      Some are the larv[ae] of species of Tinea (as Tinea
      tapetzella); others of beetles, esp. Anthrenus.

   Carpet snake (Zool.), an Australian snake. See Diamond
      snake, under Diamond.

   Carpet sweeper, an apparatus or device for sweeping
      carpets.

   To be on the carpet, to be under consideration; to be the
      subject of deliberation; to be in sight; -- an expression
      derived from the use of carpets as table cover.

   Brussels carpet. See under Brussels.
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WordNet (r) 3.0 (2006):

carpet knight
    n 1: a knight who spends his time in luxury and idleness
         (knighted on the carpet at court rather than on the field
         of battle)