a. Math. [ad. Fr. anharmonique, f. Gr. ἀν- not + ἀρμονικ-ός HARMONIC.] Not harmonic. Applied to the section of a line by four points A, B, C, D, when their mutual distances are such that AB/CB is unequal to AD/CD; the ratio between these two quotients is called the anharmonic ratio of AC.
1863. Salmon, Conic Sect., 57. This ratio is called the Anharmonic ratio of the pencil.
1866. C. J. C. Price, Tril. Co-ordinates, 45. For a system of four points (or lines) there are but six different Anharmonic ratios.
1881. Athenæum, 13 Aug., 205/1. Subjects of a higher order, such as … anharmonic section.
