Har-mŏn'ic or Har-mŏn'ic-al1, a.
a. [Fr. harmonique, Pr. armonic, Sp. & It. armonico, Pg. harmonico, Lat. harmonicus, Gr. ἁρμονικός. See HARMONY.]
Sense 1. Concordant; musical; consonant; as, harmonic sounds. “Harmonic twang of leather, horn, and brass.” Pope.
Sense 2. (Mus.) Relating to harmony or music; harmonious; especially relating to the accessory sounds which accompany the predominant and apparent single tone of any string or sonorous body.
Sense 3. (Math.) Having relations or properties bearing some resemblance to those of musical consonances; said of numbers, terms of certain ratios, or proportions, and the like.
Harmonic triad (Mus.), the chord of a note with its third and fifth; the common chord.—Harmonical mean (Arith. & Alg.), certain relations of numbers and quantities, which bear an analogy to musical consonances.—Harmonical proportion. See PROPORTION.—Harmonical series or progression, a series of numbers such that any three consecutive terms are in harmonical proportion. Brande.