pen·tam·er·ous /pɛnˈtæmərəs/
  (a.)由五個部分組成的
  Pen·tam·er·ous a.
  1. Biol. Divided into, or consisting of, five parts; also, arranged in sets, with five parts in each set, as a flower with five sepals, five petals, five, or twice five, stamens, and five pistils.
  2. Zool. Belonging to the Pentamera.
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  pentamerous
       adj : divided into five parts; specifically, having each floral
             whorl consist of five (or a multiple of five) members;
             "pentamerous flowers"