[or.tho.clase] n [G Orthoklas, fr. orth- + Gk klasis breaking, fr. klan to break--more at clast] (1849): a mineral consisting of a monoclinic form of feldspar
ORTHOCLASE
Meaning of ORTHOCLASE in English
Merriam-Webster English vocab. Английский словарь Merriam Webster. 2012