commutation

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

• noun A substitution, exchange, or interchange.
• noun The substitution of one kind of payment for another.
• noun The payment substituted.
• noun The travel of a commuter.
• noun Conversion of alternating to unidirectional current.
• noun Reversal of current direction.
• noun Law Reduction of a penalty to a less severe one.

from The Century Dictionary.

• noun A passing from one state to another; alteration; change.
• noun The act of giving one thing for another; exchange; barter.
• noun The act of substituting one thing for another; substitution.
• noun Specifically— In law, the change of a penalty or punishment from a greater to a less, as banishment instead of death.
• noun The substitution of one sort of payment for another, or of a money payment in lieu of the performance of compulsory duty or labor, or of a single payment in lieu of a number of successive payments, usually at a reduced rate. See commutation-ticket.
• noun Milit., the money value of allowances, such as quarters, fuel, forage, etc., taken in place of them.

from the GNU version of the Collaborative International Dictionary of English.

• noun rare A passing from one state to another; change; alteration; mutation.
• noun obsolete The act of giving one thing for another; barter; exchange.
• noun (Law) The change of a penalty or punishment by the pardoning power of the State.
• noun A substitution, as of a less thing for a greater, esp. a substitution of one form of payment for another, or one payment for many, or a specific sum of money for conditional payments or allowances.
• noun regular travel from a place of residence to a place where one's daily work is performed; commuting. Most often, such travel is performed between a suburb and a nearby city.
• noun (Astron.) the difference of the geocentric longitudes of the sun and a planet.
• noun the substitution of a regular payment, chargeable to the land, for the annual tithes in kind.
• noun a ticket, as for transportation, which is the evidence of a contract for service at a reduced rate. See 2d Commute, 2.

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

• noun obsolete A passing from one state to another; change; alteration; mutation.
• noun obsolete The act of giving one thing for another; barter; exchange.
• noun Substitution of one thing for another; interchange.
• noun Specifically, the substitution of one kind of payment for another, especially a switch to monetary payment from obligations of labour.
• noun law The change to a lesser penalty or punishment by the State
• noun linguistics Substitution, as a means of discriminating between phonemes.
• noun electronics The reversal of an electric current.

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

• noun (law) the reduction in severity of a punishment imposed by law
• noun a warrant substituting a lesser punishment for a greater one
• noun the travel of a commuter
• noun the act of putting one thing or person in the place of another: