Definition: progression

Source: WordNet (r) 1.7

progression
     n 1: a series with a definite pattern of advance [syn: patterned
          advance]
     2: a movement forward; "he listened for the progress of the
        troops" [syn: progress, advance]
     3: the act of moving forward toward a goal [syn: progress, advance,
         advancement, forward motion, onward motion]

Source: Webster's Revised Unabridged Dictionary (1913)

Progression \Pro*gres"sion\, n. [L. progressio: cf. F.
   progression.]
   1. The act of moving forward; a proceeding in a course;
      motion onward.

   2. Course; passage; lapse or process of time.

            I hope, in a short progression, you will be wholly
            immerged in the delices and joys of religion.
                                                  --Evelyn.

   3. (Math.) Regular or proportional advance in increase or
      decrease of numbers; continued proportion, arithmetical,
      geometrical, or harmonic.

   4. (Mus.) A regular succession of tones or chords; the
      movement of the parts in harmony; the order of the
      modulations in a piece from key to key.

   Arithmetical progression, a progression in which the terms
      increase or decrease by equal differences, as the numbers
      [lbrace2]2, 4, 6, 8, 1010, 8, 6, 4, 2[rbrace2] by the
      difference 2.

   Geometrical progression, a progression in which the terms
      increase or decrease by equal ratios, as the numbers
      [lbrace2]2, 4, 8, 16, 32, 6464, 32, 16, 8, 4, 2[rbrace2]
      by a continual multiplication or division by 2.

   Harmonic progression, a progression in which the terms are
      the reciprocals of quantities in arithmetical progression,
      as 1/2, 1/4, 1/6, 1/8, 1/10.

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.