Definition of selachian
: any of a variously classified group (Selachii) of cartilaginous fishes that includes the existing sharks and typically most related elasmobranchs (as rays)
Origin and Etymology of selachian
ultimately from Greek selachos cartilaginous phosphorescent fish; akin to Greek selas brightness
First Known Use: 1835
Seen and Heard
What made you want to look up selachian? Please tell us where you read or heard it (including the quote, if possible).