Merriam-Webster Logo
SINCE 1828
Menu
dictionary thesaurus

periclase

noun
peri·​clase | \ ˈperəˌklās, -āz\
variants: or periclasite \ ˌperəˈklā|ˌsīt , pəˈriklə| , |ˌzīt \
plural -s

Definition of periclase

: native magnesia MgO in granular forms or isometric crystals (hardness 6, specific gravity 3.67–3.90)

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 periclase

periclase from German periklas, modification of Italian periclasia, from Greek periklasis act of twisting or breaking around (from periklan to twist around, break around—from peri- + klan to break—+ -sis) + -ia -y (from Latin); periclasite from periclase + -ite (lame)

Keep scrolling for more

Learn More about periclase

Statistics for periclase

Look-up Popularity

Comments on periclase

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

Show Comments  Hide Comments 

WORD OF THE DAY

yen

Listen to the pronounciation of yen

a strong desire or propensity

Get Word of the Day daily email!

Test Your Vocabulary

Challenging Vocabulary Quiz Returns!

  • stylized drawing of woman pole vaulting across gap to get trophy
  • Which is a synonym of fuliginous?
Name That Thing

Test your visual vocabulary with our 10-question challenge!

TAKE THE QUIZ
Word Winder's CrossWinder

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