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.] candlepower

WordNet (r) 3.0 (2006):

candlepin
    n 1: a bowling pin that is thin by comparison with a tenpin