# Ordinate

**ORDINATE**, in the Cartesian system of co-ordinates, the distance of a point from the horizontal axis (axis of x) measured parallel to the
axis of y. Thus PR is the ordinate of P. The word appears to have been first used by Rene Descartes, and to be derived from lincae ordinatae, a term used by
Roman surveyors for parallel lines. (See Geometry: Analytical.)

*Note - this article incorporates content from Encyclopaedia Britannica, Eleventh Edition, (1910-1911)*