commutation

(kŏmˌyə-tāˈshən)

1. A substitution, exchange, or interchange.
2. a. The substitution of one kind of payment for another.
   b. The payment substituted.
3. The travel of a commuter.
4. Electricity
   a. Conversion of alternating to unidirectional current.
   b. Reversal of current direction.
5. Law Reduction of a penalty to a less severe one.