Meaning

noun the act of passing something along from one person or group to another

noun a crew of workers who relieve another crew

noun a fresh team to relieve weary draft animals

originFrom Middle French relai (“reserve pack of hounds”), from relaier (“to exchange tired animals for fresh”); literally, "to leave behind", from Old French relaier (“to leave behind”), from re- + laier (“to leave”), of uncertain origin.

Etymology from Wiktionary, CC BY-SA 3.0