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