selachian
noun
se·la·chi·an sə-ˈlā-kē-ən 
: any of a variously classified group (Selachii) of cartilaginous fishes that includes the existing sharks and typically most related elasmobranchs (such as rays)
selachian adjective
Word History
Etymology
ultimately from Greek selachos cartilaginous phosphorescent fish; akin to Greek selas brightness
First Known Use
1835, in the meaning defined above