From Longman Dictionary of Contemporary Englishpacemakerpace‧mak‧er /ˈpeɪsˌmeɪkə $ -ər/ noun [countable] 1 MHa small machine that is placed inside someone’s chest in order to help their heart beat regularly2 (also pacesetter) a person or horse who goes to the front in a race and sets the speed that the others must try to achieve
Examples from the Corpus
pacemaker• His pals from the Cheltenham club are going to take it in turn to swim alongside as pacemakers and companions.• Some have speculated that the headaches may be related to a periodically discharging biologic pacemaker, perhaps located in the hypothalamus.• The aim is to stay in touch with the promotion pacemakers before a run-in of five home games out of seven.• Hetton are only a point off the pacemakers after they won by six wickets Langley. 