What is "cyclostome"

Cyclostome \Cy"clo*stome\ (s?"kl?-st?m), Cyclostomous \Cy*clos"to*mous\ (s?-kl?s"t?-m?s), a. (Zo["o]l.) Pertaining to the Cyclostomi. [1913 Webster] ||

n. Any of various primitive jawless fish of the class Cyclostomata, such as the lamprey or hagfish.

n. primitive aquatic vertebrate

Cyclostome is a biological term (from the Greek for "round mouth") used in a few different senses:

• for the taxon Cyclostomata, which comprises the extant jawless fishes: the hagfish (Myxini) and the lampreys (Petromyzontidae). This was thought for a time to be a paraphyletic group and this usage of the term was deprecated by some. However, there is strong molecular evidence for cyclostome monophyly, and thus the term remains in use.
• for the Order Cyclostomatida of bryozoans, tiny animals that live in colonies and form large calcitic skeletons
• for one of two subgroups of braconid wasps