**Tau"to*chrone** (?), n. [Gr. , for the same + time: cf. F. *tautochrone*.] Math.

A curved line, such that a heavy body, descending along it by the action of gravity, will always arrive at the lowest point in the same time, wherever in the curve it may begin to fall; as, an inverted cycloid with its base horizontal is a **tautochrone**.

© Webster 1913.