The Collaborative International Dictionary of English v.0.48:

Compass \Com"pass\ (k[u^]m"pas), n. [F. compas, fr. LL.
   compassus circle, prop., a stepping together; com- + passus
   pace, step. See Pace, Pass.]
   1. A passing round; circuit; circuitous course.
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            They fetched a compass of seven day's journey. --2
                                                  Kings iii. 9.
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            This day I breathed first; time is come round,
            And where I did begin, there shall I end;
            My life is run his compass.           --Shak.
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   2. An inclosing limit; boundary; circumference; as, within
      the compass of an encircling wall.
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   3. An inclosed space; an area; extent.
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            Their wisdom . . . lies in a very narrow compass.
                                                  --Addison.
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   4. Extent; reach; sweep; capacity; sphere; as, the compass of
      his eye; the compass of imagination.
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            The compass of his argument.          --Wordsworth.
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   5. Moderate bounds, limits of truth; moderation; due limits;
      -- used with within.
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            In two hundred years before (I speak within
            compass), no such commission had been executed.
                                                  --Sir J.
                                                  Davies.
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   6. (Mus.) The range of notes, or tones, within the capacity
      of a voice or instrument.
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            You would sound me from my lowest note to the top of
            my compass.                           --Shak.
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   7. An instrument for determining directions upon the earth's
      surface by means of a magnetized bar or needle turning
      freely upon a pivot and pointing in a northerly and
      southerly direction.
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            He that first discovered the use of the compass did
            more for the supplying and increase of useful
            commodities than those who built workhouses.
                                                  --Locke.
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   8. A pair of compasses. [R.] See Compasses.

            To fix one foot of their compass wherever they
            please.                               --Swift.
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   9. A circle; a continent. [Obs.]
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            The tryne compas [the threefold world containing
            earth, sea, and heaven. --Skeat.]     --Chaucer.
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   Azimuth compass. See under Azimuth.

   Beam compass. See under Beam.

   Compass card, the circular card attached to the needles of
      a mariner's compass, on which are marked the thirty-two
      points or rhumbs.

   Compass dial, a small pocket compass fitted with a sundial
      to tell the hour of the day.

   Compass plane (Carp.), a plane, convex in the direction of
      its length on the under side, for smoothing the concave
      faces of curved woodwork.

   Compass plant, Compass flower (Bot.), a plant of the
      American prairies (Silphium laciniatum), not unlike a
      small sunflower; rosinweed. Its lower and root leaves are
      vertical, and on the prairies are disposed to present
      their edges north and south.
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            Its leaves are turned to the north as true as the
            magnet:
            This is the compass flower.           --Longefellow.

   Compass saw, a saw with a narrow blade, which will cut in a
      curve; -- called also fret saw and keyhole saw.

   Compass timber (Shipbuilding), curved or crooked timber.

   Compass window (Arch.), a circular bay window or oriel
      window.

   Mariner's compass, a kind of compass used in navigation. It
      has two or more magnetic needles permanently attached to a
      card, which moves freely upon a pivot, and is read with
      reference to a mark on the box representing the ship's
      head. The card is divided into thirty-two points, called
      also rhumbs, and the glass-covered box or bowl containing
      it is suspended in gimbals within the binnacle, in order
      to preserve its horizontal position.

   Surveyor's compass, an instrument used in surveying for
      measuring horizontal angles. See Circumferentor.

   Variation compass, a compass of delicate construction, used
      in observations on the variations of the needle.

   To fetch a compass, to make a circuit.
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The Collaborative International Dictionary of English v.0.48:

Keyhole \Key"hole`\, n.
   1. A hole or apertupe in a door or lock, for receiving a key.
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   2.
      (a) (Carp.) A hole or excavation in beams intended to be
          joined together, to receive the key which fastens
          them.
      (b) (Mach.) a mortise for a key or cotter.
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   Keyhole limpet (Zool.), a marine gastropod of the genus
      Fissurella and allied genera. See Fissurella.

   Keyhole saw, a narrow, slender saw, used in cutting
      keyholes, etc., as in doors; a kind of compass saw or fret
      saw.

   Keyhole urchin (Zool.), any one of numerous clypeastroid
      sea urchins, of the genera Melitta, Rotula, and
      Encope; -- so called because they have one or more
      perforations resembling keyholes.
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WordNet (r) 3.0 (2006):

keyhole saw
    n 1: a handsaw with a long narrow blade for cutting short radius
         curves; similar to a compass saw