orthoclase

noun

or·tho·clase ˈȯr-thə-ˌklās

-ˌklāz

: a monoclinic mineral of the feldspar group consisting of a silicate of potassium and aluminum

Word History

Etymology

German Orthoklas, from orth- + Greek klasis breaking, from klan to break — more at clast

First Known Use

1849, in the meaning defined above

Time Traveler

The first known use of orthoclase was in 1849

See more words from the same year

Cite this Entry

Style

“Orthoclase.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/orthoclase. Accessed 4 Nov. 2025.

Copy Citation

Kids Definition

orthoclase

noun

or·tho·clase ˈȯr-thə-ˌklās

-ˌklāz

: a mineral consisting especially of potassium feldspar

More from Merriam-Webster

Word of the Day

spontaneous

Listen to the pronunciation of spontaneous

See Definitions and Examples »

Get Word of the Day daily email!

Popular in Grammar & Usage

'Affect' vs. 'Effect'

Using Bullet Points ( • )

The Difference Between 'i.e.' and 'e.g.'

What’s the difference between ‘cemetery’ and ‘graveyard’?

Democracy or Republic: What's the difference?

Popular in Wordplay

Skibidi, Mog & More: Gen Alpha Slang

13 Wonderful Words That You're Not Using (Yet)

Ten More Words from Taylor Swift Songs

Birds Say the Darndest Things

Even More Bird Names that Sound Like Insults (and Sometimes Are)

Popular

'Affect' vs. 'Effect'

Skibidi, Mog & More: Gen Alpha Slang

13 Wonderful Words That You're Not Using (Yet)