Brachystochrone

Bra`chys´to`chrone

n.

1.

(Math.) A curve, in which a body, starting from a given point, and descending solely by the force of gravity, will reach another given point in a shorter time than it could by any other path. This curve of quickest descent, as it is sometimes called, is, in a vacuum, the same as the cycloid.

Webster's Revised Unabridged Dictionary, published 1913 by G. & C. Merriam Co.