Dynastidan

n. [ Gr. &unr_;, fem. of &unr_;. See Dynast. The name alludes to the immense size of some species. ] (Zool.) One of a group of gigantic, horned beetles, including Dynastus Neptunus, and the Hercules beetle (Dynastus Hercules) of tropical America, which grow to be six inches in length. [ 1913 Webster ]