Learner's definition of DRUMMER
: a person who plays a drum or a set of drums
— used in phrases like march to the beat of a different drummer to describe a person who thinks, lives, or behaves in an unusual way
His strange behavior was no surprise—he had always marched to (the beat of) a different drummer. [=done things differently from other people]
Her friends went to college, but she heard a different drummer and moved to the city to be an actor.