/ Dictionary / Index G greisen: Meaning and Definition of Find definitions for: grei•sen Pronunciation: (grī'zun), [key] — n. a hydrothermally altered rock of granitic texture composed chiefly of quartz and mica, common in the tin mines of Europe. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: greisen (Thesaurus) greige gremial Related Content Daily Word Quiz: neologism Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language