What is "slope of a plane"

Slope \Slope\, n. [Formed (like abode fr. abide) from OE. slipen. See Slip, v. i.]

1. An oblique direction; a line or direction including from a horizontal line or direction; also, sometimes, an inclination, as of one line or surface to another.

2. Any ground whose surface forms an angle with the plane of the horizon.

   buildings the summit and slope of a hill.
   --Macaulay.

   Under the slopes of Pisgah.
   --Deut. iv. 49. (Rev. Ver.).

3. The part of a continent descending toward, and draining to, a particular ocean; as, the Pacific slope.

   Note: A slope, considered as descending, is a declivity; considered as ascending, an acclivity.

   Slope of a plane (Geom.), the direction of the plane; as, parallel planes have the same slope.