The Collaborative International Dictionary of English v.0.48:
Cheerer \Cheer"er\ (ch[=e]r"[~e]r), n. One who cheers; one who, or that which, gladdens. "Thou cheerer of our days." --Wotton. "Prime cheerer, light." --Thomson. [1913 Webster]WordNet (r) 3.0 (2006):
cheerer n 1: a spectator who shouts encouragement