The Collaborative International Dictionary of English v.0.48:

Holothurian \Hol`o*thu"ri*an\, a. (Zool.)
   Belonging to the Holothurioidea. -- n. One of the
   Holothurioidea.
   [1913 Webster]

   Note: Some of the species of Holothurians are called sea
         cucumbers, sea slugs, trepang, and b[^e]che de
         m[`e]r. Many are used as food, esp. by the Chinese.
         See Trepang.
         [1913 Webster]