The Collaborative International Dictionary of English v.0.48:
Candlepin \Can`dle*pin`\, n. (Tenpins) (a) A form of bowling pin slender and nearly straight like a candle. (b) The game played with such pins; -- in form candlepins, used as a singular. [Webster 1913 Suppl.] candlepowerWordNet (r) 3.0 (2006):
candlepin n 1: a bowling pin that is thin by comparison with a tenpin