an officer of the highest rank in the army or air force of some countries:
the Marshal of the Royal Airforce
an official in charge of an important public event or ceremony:
Heston has been named grand marshal of the parade.
a person who controls crowds, traffic etc at a sports event or other public event:
I could see a marshal on the finish line waving a yellow flag.
4 American EnglishSCL
a police officer employed by the national government to make sure people do what a court order says they must do
5 American English
the officer in charge of a fire department