/ Dictionary / Index G gneissoid: Meaning and Definition of Find definitions for: gneiss•oid Pronunciation: (nī'soid), [key] — adj. resembling gneiss. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. gneiss Gniezno Related Content Daily Word Quiz: perspicacious Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language