\Go`ni*om"e*ter\, n. [Gr. ? angle + -meter: cf. F.
goniom[`e]tre.]
An instrument for measuring angles, especially the angles of
crystals, or the inclination of planes.
{Contact, or Hand}, {goniometer}, a goniometer having two
   movable arms (ab, cd), between which (at ab) the faces of
   the crystals are placed. These arms turn about a fixed
   point, which is the center of the graduated circle or
   semicircle upon which the angle is read off.
{Reflecting goniometer}, an instrument for measuring the
   angles of crystals by determining through what angular
   space the crystal must be turned so that two rays
   reflected from two surfaces successively shall have the
   same direction; -- called also {Wollaston's goniometer},
   from the inventor.