there are multiple defonitions:
an instruction, command, or duty given to a person or group of people.
"he received a commission to act as an informer"
a group of people officially charged with a particular function.
"the United Nations High Commission for Refugees"
an amount of money, typically a set percentage of the value involved, paid to an agent in a commercial transaction.
"foreign banks may charge a commission"
a warrant conferring the rank of officer in an army, navy, or air force.
"he has resigned his commission"
