n. [ Gr.&unr_; path + graph. ] (Math.) A curve described by the moving extremity of a line the other end of which is fixed, this line being constantly parallel to the direction of motion of, and having its length constantly proportional to the velocity of, a point moving in any path; -used in investigations respecting central forces. [ 1913 Webster ]

n. [ Gr. "odo`metron, "odo`metros, an instrument for measuring distance; "odo`s way, path, road + me`tron measure: cf. F. odométre, hodométre. See also odometer.] A device for measuring the length of a path, consisting of a wheel of known circumference attached to a rod held in the hand, and pushed along a surface, which is usually the ground or a floor. The number of times the wheel makes a complete circle multiplied by the circumference is a measure of the length of the path traversed. It may be used to measure distances on curved as well as straight paths. A variant which registers the miles and rods traversed is sometimes used by surveyors. [PJC + 1913 Webster]