simple machine

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

• noun Any of numerous basic devices that alter the magnitude or direction, or both, of an applied force, traditionally including the lever, wedge, inclined plane, wheel and axle, pulley, and screw.

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

• noun physics A device that only requires the application of a single force to work.

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

• noun a device for overcoming resistance at one point by applying force at some other point