plural noun
Se·​la·​chii | \ -kēˌī\

Definition of Selachii

in some classifications
: a variously delimited group of elasmobranch fishes:
a : a primary division of Pisces that includes all the elasmobranchs and is equivalent to Chondrichthyes
b : a class or subclass that includes all the elasmobranchs except the chimaeras
c : a subclass or order that includes the existing sharks and rays as distinguished from the extinct Pleuropterygii and Ichthyotomi
d : a suborder that includes the existing sharks as distinguished from the rays and is equivalent to Pleurotremata

Love words?

You must — there are over 200,000 words in our free online dictionary, but you are looking for one that’s only in the Merriam-Webster Unabridged Dictionary.

Start your free trial today and get unlimited access to America's largest dictionary, with:

  • More than 250,000 words that aren't in our free dictionary
  • Expanded definitions, etymologies, and usage notes
  • Advanced search features
  • Ad free!

History and Etymology for Selachii

New Latin, irregular from selachos cartilaginous fish; akin to Greek selas light, brightness

Keep scrolling for more

Comments on Selachii

What made you want to look up Selachii? Please tell us where you read or heard it (including the quote, if possible).


transposition of initial sounds of words

Get Word of the Day daily email!

Test Your Vocabulary

Word Puzzles

  • alt 57589b2b4c6a3
  • Which answer pairs best with each of the following words? living, estate, club, music, road, mile
Spell It

Can you spell these 10 commonly misspelled words?

Syn City

Test Your Knowledge - and learn some interesting things along the way.

Love words? Need even more definitions?

Subscribe to America's largest dictionary and get thousands more definitions and advanced search—ad free!