The Collaborative International Dictionary of English v.0.48:

Madrepora \Mad`re*po"ra\ (m[a^]d`r[-e]*p[=o]"r[.a]), n. [NL. See
   Madrepore.] (Zool.)
   A genus of reef corals abundant in tropical seas. It includes
   than one hundred and fifty species, most of which are
   elegantly branched. -- Mad`re*po"ral, a.
   [1913 Webster]