**Har*mon"ic** (?), **Har*mon"ic*al** (), a. [L. *harmonicus*, Gr. ; cf. F. *harmonique*. See Harmony.]

**1.**

Concordant; musical; consonant; as, **harmonic** sounds.

Harmonic twang! of leather, horn, and brass.
*Pope.*

**2.** Mus.

Relating to harmony, -- as *melodic* relates to melody; harmonious; esp., relating to the accessory sounds or overtones which accompany the predominant and apparent single tone of any string or sonorous body.

**3.** Math.

Having relations or properties bearing some resemblance to those of musical consonances; -- said of certain numbers, ratios, proportions, points, lines. motions, and the like.

Harmonic interval Mus., the distance between two notes of a chord, or two consonant notes. -- Harmonical mean Arith. & Alg., certain relations of numbers and quantities, which bear an analogy to musical consonances. -- Harmonic motion, <-- reference to diagram of a circle with radius having point P on the circle, and a diameter with point A in the diameter. THe motion of point A, plotted over time, will describe a sine wave! -->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 ∨ 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.

© Webster 1913.