English▸ noun
1 a person or animal who sets the pace at the beginning of a race, sometimes in order to help a runner break a record:
he acted as a pacemaker for Bannister when he broke the four-minute mile.
▪ a person who sets standards of achievement for others:
unbeaten Rangers are the surprise pacemakers.
2 a device for stimulating the heart muscle and regulating its contractions.
▪ the part of the heart muscle (the sino-atrial node) which normally regulates contractions.
▪ the part of an organ or of the body which controls rhythmic physiological activity:
the brain's circadian pacemaker which regulates our ‘biological clock’.