**An`har*mon"ic** (#), a. [F. *anharmonique*, fr. Gr. priv. + harmonic.] Math.

Not harmonic.

The anharmonic function or ratio of four points *abcd** on a straight line is the quantity (ac/ad):(bc/bd), where the segments are to regarded as plus or minus, according to the order of the letters.
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*© Webster 1913.*