mechanical advantage

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

• noun The ratio of the output force produced by a machine to the applied input force.

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

• noun The ratio of the output force produced by a machine (especially a simple machine) to the applied input force.

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

• noun the ratio of the force exerted by a machine to the force applied to it