Synonyms for Commutation (same or very similar meaning)
WordNet sense 1 ((law) the reduction in severity of a punishment imposed by law):
re-sentencingWordNet sense 2 (the travel of a commuter):
commutingWordNet sense 3 (the act of putting one thing or person in the place of another:):
exchange, substitutionFrom the ODE community, based on WordNetadd/edit