Definition of 'relay'. relay. Word forms: plural , 3rd person singular present tense relays, present participle relaying , past tense , past participle relayed pronunciation note: The noun is pronounced (riːleɪ ). The verb is pronounced (rɪleɪ ). A relay or a relay race is a race between two or more teams, for example teams of runners or swimmers. Each member of the team runs or swims one section of the race. Britain's prospects of beating the United States in the relay looked poor.