The Collaborative International Dictionary of English v.0.48:

Miter \Mi"ter\, Mitre \Mi"tre\, n. [F. mitre, fr. L. mitra
   headband, turban, Gr. ?.]
   1. A covering for the head, worn on solemn occasions by
      bishops and other church dignitaries. It has been made in
      many forms, the present form being a lofty cap with two
      points or peaks. --Fairholt.
      [1913 Webster]

   2. The surface forming the beveled end or edge of a piece
      where a miter joint is made; also, a joint formed or a
      junction effected by two beveled ends or edges; a miter
      joint.
      [1913 Webster]

   3. (Numis.) A sort of base money or coin.
      [1913 Webster]

   Miter box (Carp. & Print.), an apparatus for guiding a
      handsaw at the proper angle in making a miter joint; esp.,
      a wooden or metal trough with vertical kerfs in its
      upright sides, for guides.

   Miter dovetail (Carp.), a kind of dovetail for a miter
      joint in which there is only one joint line visible, and
      that at the angle.

   Miter gauge (Carp.), a gauge for determining the angle of a
      miter.

   Miter joint, a joint formed by pieces matched and united
      upon a line bisecting the angle of junction, as by the
      beveled ends of two pieces of molding or brass rule, etc.
      The term is used especially when the pieces form a right
      angle, such as the edges of a window frame, and the edge
      of each piece at the point of junction is cut at a 45[deg]
      angle to its long direction. See Miter, 2.

   Miter shell (Zool.), any one of numerous species of marine
      univalve shells of the genus Mitra.

   Miter square (Carp.), a bevel with an immovable arm at an
      angle of 45[deg], for striking lines on stuff to be
      mitered; also, a square with an arm adjustable to any
      angle.

   Miter wheels, a pair of bevel gears, of equal diameter,
      adapted for working together, usually with their axes at
      right angles.
      [1913 Webster] Miter

The Collaborative International Dictionary of English v.0.48:

Miter \Mi"ter\, Mitre \Mi"tre\, v. t. [imp. & p. p. Miteredor
   Mitred; p. pr. & vb. n. Miteringor Mitring.]
   1. To place a miter upon; to adorn with a miter. [WordNet
      sense 2] "Mitered locks." --Milton.
      [1913 Webster]

   2. To match together, as two pieces of molding or brass rule
      on a line bisecting the angle of junction; to fit together
      in a miter joint. [WordNet sense 3]
      [1913 Webster]

   3. To bevel the ends or edges of, for the purpose of matching
      together at an angle. [WordNet sense 1]
      [1913 Webster] Miter

The Collaborative International Dictionary of English v.0.48:

Miter \Mi"ter\, Mitre \Mi"tre\, v. i.
   To meet and match together, as two pieces of molding, on a
   line bisecting the angle of junction.
   [1913 Webster]

WordNet (r) 3.0 (2006):

miter
    n 1: joint that forms a corner; usually both sides are bevelled
         at a 45-degree angle to form a 90-degree corner [syn:
         miter joint, mitre joint, miter, mitre]
    2: the surface of a beveled end of a piece where a miter joint
       is made; "he covered the miter with glue before making the
       joint" [syn: miter, mitre]
    3: a liturgical headdress worn by bishops on formal occasions
       [syn: miter, mitre]
    v 1: bevel the edges of, to make a miter joint
    2: confer a miter on (a bishop)
    3: fit together in a miter joint

Moby Thesaurus II by Grady Ward, 1.0:

80 Moby Thesaurus words for "miter":
   ankle, articulate, articulation, batten, batten down, bolt,
   boundary, buckle, butt, button, cervix, clasp, cleat, clinch, clip,
   closure, connecting link, connecting rod, connection, coupling,
   crook, crosier, dovetail, elbow, embrace, gliding joint, hasp,
   hinge, hinged joint, hip, hitch, hook, interface, jam, join,
   joining, joint, juncture, keys, knee, knuckle, latch, link, lock,
   mortise, nail, neck, pallium, pastoral staff, peg, pin, pivot,
   pivot joint, rabbet, red hat, ring, rivet, scarf, screw, seam, sew,
   shoulder, skewer, snap, staple, stick, stitch, suture, symphysis,
   tack, tiara, tie rod, toggle, toggle joint, triple crown, union,
   wedge, weld, wrist, zipper