anorthosite: Meaning and Definition of

an•or•tho•site

Pronunciation: (an-ôr'thu-sīt"), [key]
— n. Petrol.
  1. a granular plutonic rock composed largely of labradorite or a more calcic feldspar.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.