noun peri·clase \ˈperəˌklās, -āz\
variants: or


\ˌperəˈklā|ˌsīt, pəˈriklə|, |ˌzīt\

Definition of periclase



  1. :  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.

Join MWU now and get access to America’s largest dictionary, with:

  • 300,000 words that aren't in our free dictionary
  • Expanded definitions, etymologies, and usage notes
  • Advanced search features
  • Ad free!

Origin and Etymology of 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 — more at halt (lame)

Seen and Heard

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


to cast off or become cast off

Get Word of the Day daily email!