king·pin /ˈkɪŋˌpɪn/
  [保齡球] 中央瓶;五號瓶
  kingpin
       n 1: the most important person in a group or undertaking [syn: top
            banana, bigwig]
       2: bolt that provides a steering joint in a motor vehicle [syn:
           kingbolt, swivel pin]
       3: the front bowling pin in the triangular arrangement of ten
          pins [syn: headpin]