/ Dictionary / Index M methylthionine chloride: Meaning and Definition of Find definitions for: meth•yl•thi'o•nine chlo'ride Pronunciation: (meth"ul-thī'u-nēn", -nin), [key] — Chem. Chem. See Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. methyltheobromine methyl transferase 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