Merriam-Webster Logo
SINCE 1828
Menu
dictionary thesaurus

Ephemeridae

plural noun
Eph·​e·​mer·​i·​dae | \ -əˌdē\

Definition of Ephemeridae

: a family of large mayflies that include forms having shining transparent wings as adults and as nymphs very large mandibles curved out at the tips, feathered gills extending over the body, and enlarged front legs adapted for digging in stream and lake bottoms

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 Ephemeridae

New Latin, from Ephemera, type genus + -idae

Keep scrolling for more

Learn More about Ephemeridae

Share Ephemeridae

Statistics for Ephemeridae

Look-up Popularity

Comments on Ephemeridae

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

Show Comments  Hide Comments 

WORD OF THE DAY

orthography

Listen to the pronounciation of orthography

the way words of a language are spelled

Get Word of the Day daily email!

Test Your Vocabulary

A Green Quiz

  • shamrock
  • What is the best definition of green-eyed monster?
How Strong Is Your Vocabulary?

Test your vocabulary with our 10-question quiz!

TAKE THE QUIZ
SCRABBLE® Sprint

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

TAKE THE QUIZ

Love words? Need even more definitions?

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

Words at Play

Ask the Editors

Word Games