[ an-awr-thuh-sahyt ]
/ ænˈɔr θəˌsaɪt /

noun Petrology.

a granular plutonic rock composed largely of labradorite or a more calcic feldspar.

Origin of anorthosite

1860–65; < French anorthose anorthoclase (an- an-1 + Greek orthós straight) + -ite1

Related forms

an·or·tho·sit·ic [an-aw-thuh-sit-ik] /ænˌɔ θəˈsɪt ɪk/, adjective Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

Examples from the Web for anorthosite

British Dictionary definitions for anorthosite


/ (ænˈɔːθəˌsaɪt) /


a coarse-grained plutonic igneous rock consisting almost entirely of plagioclase feldspar

Word Origin for anorthosite

C19: from French anorthose (see an-, ortho-) + -ite 1
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Science definitions for anorthosite


[ ăn-ôrthə-sīt′ ]

An igneous rock consisting almost entirely of plagioclase feldspar, especially the labradorite variety. Anorthosites have been identified among rock samples collected from the Moon.
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