/ Dictionary / Index M methimazole: Meaning and Definition of Find definitions for: meth•im•a•zole Pronunciation: (me-thim'u-zōl", -thī'mu-), [key] — n. Pharm. a white crystalline substance, CHNS, that inhibits thyroxin synthesis, used in the treatment of hyperthyroidism. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. methicillin methinks Related Content Daily Word Quiz: immense Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language