inclined plane

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun A plane set at an angle to the horizontal, especially a simple machine used to raise or lower a load by rolling or sliding.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun One of the simple machines; a sloping surface such as a ramp such that an object can be raised with less effort than being lifted vertically.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun a simple machine for elevating objects; consists of plane surface that makes an acute angle with the horizontal