Source : Webster's Revised Unabridged Dictionary (1913)

the motion of the point A, of the foot of the perpendicular PA,
when P moves uniformly in the circumference of a circle, and PA
is drawn perpendicularly upon a fixed diameter of the circle.
This is simple harmonic motion. The combinations, in any way, of
two more simple harmonic motions, make other kinds of harmonic
motion. The motion of the pendulum bob of a clock is
approximately simple harmonic motion.

   {Harmonic proportion}. See under {Proportion}.

   {Harmonic series} or {progression}. See under {Progression}.
      

   {Spherical harmonic analysis}, a mathematical method,
      sometimes referred to as that of Laplace's Coefficients,
      which has for its object the expression of an arbitrary,
      periodic function of two independent variables, in the
      proper form for a large class of physical problems,
      involving arbitrary data, over a spherical surface, and
      the deduction of solutions for every point of space. The
      functions employed in this method are called spherical
      harmonic functions. --Thomson & Tait.

   {Harmonic suture} (Anat.), an articulation by simple
      apposition of comparatively smooth surfaces or edges, as
      between the two superior maxillary bones in man; -- called
      also {harmonic}, and {harmony}.

   {Harmonic triad} (Mus.), the chord of a note with its third
      and fifth; the common chord.