commission has 11 distinct synonyms spread across 7 of its 12 senses. Each sense below keeps its own list, because a synonym belongs to a meaning and not to a word: swapping one sense's substitute into another sense's sentence is how a thesaurus makes writing worse. WordNet records no antonym for it — antonymy is a relation between word forms rather than concepts, so it is deliberately sparse.
Counts are distinct word forms across every sense. A synonym that appears under three senses is counted once here and shown three times below, under each sense it belongs to.
a special group delegated to consider some matter
“a committee is a group that keeps minutes and loses hours”
a fee for services rendered based on a percentage of an amount received or collected or agreed to be paid (as distinguished from a salary)
“he works on commission”
the act of granting authority to undertake certain functions
the state of being in good working order and ready for operation
“put the ships into commission”
a group of representatives or delegates
a formal statement of a command or injunction to do something
“the judge's charge to the jury”
an official document issued by a government and conferring on the recipient the rank of an officer in the armed forces
a special assignment that is given to a person or group
“a confidential mission to London”
put into commission; equip for service; of ships
charge with a task
Synonyms, antonyms and the broader and narrower relations for commission come from Princeton University’s WordNet. Full sources and licences.