The Collaborative International Dictionary of English v.0.48:

Crab \Crab\ (kr[a^]b), n. [AS. crabba; akin to D. krab, G.
   krabbe, krebs, Icel. krabbi, Sw. krabba, Dan. krabbe, and
   perh. to E. cramp. Cf. Crawfish.]
   1. (Zool.) One of the brachyuran Crustacea. They are mostly
      marine, and usually have a broad, short body, covered with
      a strong shell or carapace. The abdomen is small and
      curled up beneath the body.
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   Note: The name is applied to all the Brachyura, and to
         certain Anomura, as the hermit crabs. Formerly, it was
         sometimes applied to Crustacea in general. Many species
         are edible, the blue crab of the Atlantic coast being
         one of the most esteemed. The large European edible
         crab is Cancer padurus. Soft-shelled crabs are blue
         crabs that have recently cast their shells. See
         Cancer; also, Box crab, Fiddler crab, Hermit
         crab, Spider crab, etc., under Box, Fiddler.
         etc.
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   2. The zodiacal constellation Cancer.
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   3. [See Crab, a.] (Bot.) A crab apple; -- so named from its
      harsh taste.
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            When roasted crabs hiss in the bowl,
            Then nightly sings the staring owl.   --Shak.
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   4. A cudgel made of the wood of the crab tree; a crabstick.
      [Obs.] --Garrick.
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   5. (Mech.)
      (a) A movable winch or windlass with powerful gearing,
          used with derricks, etc.
      (b) A form of windlass, or geared capstan, for hauling
          ships into dock, etc.
      (c) A machine used in ropewalks to stretch the yarn.
      (d) A claw for anchoring a portable machine.
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   Calling crab. (Zool.) See Fiddler., n., 2.

   Crab apple, a small, sour apple, of several kinds; also,
      the tree which bears it; as, the European crab apple
      (Pyrus Malus var. sylvestris); the Siberian crab apple
      (Pyrus baccata); and the American (Pyrus coronaria).


   Crab grass. (Bot.)
      (a) A grass (Digitaria sanguinalis syn. Panicum
          sanguinalis); -- called also finger grass.
      (b) A grass of the genus Eleusine (Eleusine Indica);
          -- called also dog's-tail grass, wire grass, etc.


   Crab louse (Zool.), a species of louse (Phthirius pubis),
      sometimes infesting the human body.

   Crab plover (Zool.), an Asiatic plover (Dromas ardeola).


   Crab's eyes, or Crab's stones, masses of calcareous
      matter found, at certain seasons of the year, on either
      side of the stomach of the European crawfishes, and
      formerly used in medicine for absorbent and antacid
      purposes; the gastroliths.

   Crab spider (Zool.), one of a group of spiders
      (Laterigrad[ae]); -- called because they can run
      backwards or sideways like a crab.

   Crab tree, the tree that bears crab applies.

   Crab wood, a light cabinet wood obtained in Guiana, which
      takes a high polish. --McElrath.

   To catch a crab (Naut.), a phrase used of a rower:
      (a) when he fails to raise his oar clear of the water;
      (b) when he misses the water altogether in making a
          stroke.
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The Collaborative International Dictionary of English v.0.48:

Finger \Fin"ger\ (f[i^][ng]"g[~e]r), n. [AS. finger; akin to D.
   vinger, OS. & OHG. fingar, G. finger, Icel. fingr, Sw. & Dan.
   finger, Goth. figgrs; of unknown origin; perh. akin to E.
   fang.]
   1. One of the five terminating members of the hand; a digit;
      esp., one of the four extremities of the hand, other than
      the thumb.
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   2. Anything that does the work of a finger; as, the pointer
      of a clock, watch, or other registering machine;
      especially (Mech.) a small projecting rod, wire, or piece,
      which is brought into contact with an object to effect,
      direct, or restrain a motion.
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   3. The breadth of a finger, or the fourth part of the hand; a
      measure of nearly an inch; also, the length of finger, a
      measure in domestic use in the United States, of about
      four and a half inches or one eighth of a yard.
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            A piece of steel three fingers thick. --Bp. Wilkins.
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   4. Skill in the use of the fingers, as in playing upon a
      musical instrument. [R.]
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            She has a good finger.                --Busby.
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   Ear finger, the little finger.

   Finger alphabet. See Dactylology.

   Finger bar, the horizontal bar, carrying slotted spikes, or
      fingers, through which the vibratory knives of mowing and
      reaping machines play.

   Finger board (Mus.), the part of a stringed instrument
      against which the fingers press the strings to vary the
      tone; the keyboard of a piano, organ, etc.; manual.

   Finger bowl Finger glass, a bowl or glass to hold water
      for rinsing the fingers at table.

   Finger flower (Bot.), the foxglove.

   Finger grass (Bot.), a kind of grass (Panicum sanguinale)
      with slender radiating spikes; common crab grass. See
      Crab grass, under Crab.

   Finger nut, a fly nut or thumb nut.

   Finger plate, a strip of metal, glass, etc., to protect a
      painted or polished door from finger marks.

   Finger post, a guide post bearing an index finger.

   Finger reading, reading printed in relief so as to be
      sensible to the touch; -- so made for the blind.

   Finger shell (Zool.), a marine shell (Pholas dactylus)
      resembling a finger in form.

   Finger sponge (Zool.), a sponge having finger-shaped lobes,
      or branches.

   Finger stall, a cover or shield for a finger.

   Finger steel, a steel instrument for whetting a currier's
      knife.
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   To burn one's fingers. See under Burn.

   To have a finger in, to be concerned in. [Colloq.]

   To have at one's fingers' ends, to be thoroughly familiar
      with. [Colloq.]
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WordNet (r) 3.0 (2006):

finger grass
    n 1: grasses with creeping stems that root freely; a pest in
         lawns [syn: crabgrass, crab grass, finger grass]
    2: any grass of the genus Chloris; occurs in short grassland
       especially on waste ground or poor soils