/ Dictionary / Index R rhyolite: Meaning and Definition of Find definitions for: rhy•o•lite Pronunciation: (rī'u-līt"), [key] — n. a fine-grained igneous rock rich in silica: the volcanic equivalent of granite. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: rhyolite (Thesaurus) rhynchocephalian rhythm Related Content Daily Word Quiz: cygnet Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language