[1] : The Collaborative International Dictionary of English v.0.48

symmetry \sym"metry\, n. l. symmetria, gr. ?; sy`n with,
   together + ? a measure: cf. f. sym'etrie. see syn-, and
   meter rhythm.
   1. a due proportion of the several parts of a body to each
      other; adaptation of the form or dimensions of the several
      parts of a thing to each other; the union and conformity
      of the members of a work to the whole.
      1913 webster

   2. biol. the law of likeness; similarity of structure;
      regularity in form and arrangement; orderly and similar
      distribution of parts, such that an animal may be divided
      into parts which are structurally symmetrical.
      1913 webster

   note: bilateral symmetry, or two-sidedness, in vertebrates,
         etc., is that in which the body can be divided into
         symmetrical halves by a vertical plane passing through
         the middle; radial symmetry, as in echinoderms, is that
         in which the individual parts are arranged
         symmetrically around a central axis; serial symmetry,
         or zonal symmetry, as in earthworms, is that in which
         the segments or metameres of the body are disposed in a
         zonal manner one after the other in a longitudinal
         axis. this last is sometimes called metamerism.
         1913 webster

   3. bot.
      a equality in the number of parts of the successive
          circles in a flower.
      b likeness in the form and size of floral organs of the
          same kind; regularity.
          1913 webster

   axis of symmetry. geom. see under axis.

   respective symmetry, that disposition of parts in which
      only the opposite sides are equal to each other.
      1913 webster
see also:
syn- meter axis of symmetry axis respective symmetry 

[2] : The Collaborative International Dictionary of English v.0.48

axis \ax"is\, n.; pl. axes. l. axis axis, axle. see axle.
   a straight line, real or imaginary, passing through a body,
   on which it revolves, or may be supposed to revolve; a line
   passing through a body or system around which the parts are
   symmetrically arranged.
   1913 webster

   2. math. a straight line with respect to which the
      different parts of a magnitude are symmetrically arranged;
      as, the axis of a cylinder, i. e., the axis of a cone,
      that is, the straight line joining the vertex and the
      center of the base; the axis of a circle, any straight
      line passing through the center.
      1913 webster

   3. bot. the stem; the central part, or longitudinal
      support, on which organs or parts are arranged; the
      central line of any body. --gray.
      1913 webster

   4. anat.
      a the second vertebra of the neck, or vertebra
          dentata.
      b also used of the body only of the vertebra, which is
          prolonged anteriorly within the foramen of the first
          vertebra or atlas, so as to form the odontoid process
          or peg which serves as a pivot for the atlas and head
          to turn upon.
          1913 webster

   5. crystallog. one of several imaginary lines, assumed in
      describing the position of the planes by which a crystal
      is bounded.
      1913 webster

   6. fine arts the primary or secondary central line of any
      design.
      1913 webster

   anticlinal axis geol., a line or ridge from which the
      strata slope downward on the two opposite sides.

   synclinal axis, a line from which the strata slope upward
      in opposite directions, so as to form a valley.

   axis cylinder anat., the neuraxis or essential, central
      substance of a nerve fiber; -- called also axis band,
      axial fiber, and cylinder axis.

   axis in peritrochio, the wheel and axle, one of the
      mechanical powers.

   axis of a curve geom., a straight line which bisects a
      system of parallel chords of a curve; called a principal
      axis, when cutting them at right angles, in which case it
      divides the curve into two symmetrical portions, as in the
      parabola, which has one such axis, the ellipse, which has
      two, or the circle, which has an infinite number. the two
      axes of the ellipse are the major axis and the minor
      axis, and the two axes of the hyperbola are the
      transverse axis and the conjugate axis.

   axis of a lens, the straight line passing through its
      center and perpendicular to its surfaces.

   axis of a microscope or axis of a telescope, the straight
      line with which coincide the axes of the several lenses
      which compose it.

   axes of co"ordinates in a plane, two straight lines
      intersecting each other, to which points are referred for
      the purpose of determining their relative position: they
      are either rectangular or oblique.

   axes of co"ordinates in space, the three straight lines
      in which the co"ordinate planes intersect each other.

   axis of a balance, that line about which it turns.

   axis of oscillation, of a pendulum, a right line passing
      through the center about which it vibrates, and
      perpendicular to the plane of vibration.

   axis of polarization, the central line around which the
      prismatic rings or curves are arranged. --brewster.

   axis of revolution descriptive geom., a straight line
      about which some line or plane is revolved, so that the
      several points of the line or plane shall describe circles
      with their centers in the fixed line, and their planes
      perpendicular to it, the line describing a surface of
      revolution, and the plane a solid of revolution.

   axis of symmetry geom., any line in a plane figure which
      divides the figure into two such parts that one part, when
      folded over along the axis, shall coincide with the other
      part.

   axis of the equator, ecliptic, horizon or other circle
      considered with reference to the sphere on which it lies,
      the diameter of the sphere which is perpendicular to the
      plane of the circle. --hutton.

   axis of the ionic capital arch., a line passing
      perpendicularly through the middle of the eye of the
      volute.

   neutral axis mech., the line of demarcation between the
      horizontal elastic forces of tension and compression,
      exerted by the fibers in any cross section of a girder.

   optic axis of a crystal, the direction in which a ray of
      transmitted light suffers no double refraction. all
      crystals, not of the isometric system, are either uniaxial
      or biaxial.

   optic axis, visual axis opt., the straight line passing
      through the center of the pupil, and perpendicular to the
      surface of the eye.

   radical axis of two circles geom., the straight line
      perpendicular to the line joining their centers and such
      that the tangents from any point of it to the two circles
      shall be equal to each other.

   spiral axis arch., the axis of a twisted column drawn
      spirally in order to trace the circumvolutions without.

   axis of abscissas and axis of ordinates. see abscissa.
      1913 webster
see also:
axes axle vertebra dentata anticlinal axis synclinal axis axis cylinder 
axis band axial fiber cylinder axis axis in peritrochio axis of a curve 
principal axis major axis minor axis transverse axis conjugate axis 
axis of a lens axis of a microscope axis of a telescope axes of co"ordinates in a plane axes of co"ordinates in space 
axis of a balance axis of oscillation axis of polarization axis of revolution axis of symmetry 
axis of the equator, ecliptic, horizon axis of the ionic capital neutral axis optic axis of a crystal 
optic axis visual axis radical axis of two circles spiral axis axis of abscissas 
axis of ordinates abscissa 

Axis >> A Words
Axis, definition of term: Axis
axis_pag1.html

Symmetry >> S Words
Symmetry, definition of term: Symmetry
symmetry_pag1.html

Neutral Axis >> N Words
Neutral Axis, definition of term: Neutral Axis
neutral+axis_pag1.html

Major Axis >> M Words
Major Axis, definition of term: Major Axis
major+axis_pag1.html

Coordinate Axis >> C Words
Coordinate Axis, definition of term: Coordinate Axis
coordinate+axis_pag1.html