/ Dictionary / Index M menstruum: Meaning and Definition of Find definitions for: men•stru•um Pronunciation: (men'str-um, -strum), [key] — pl. -stru•ums, -stru•a a solvent. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: menstruum (Thesaurus) menstruous mensurable Related Content Daily Word Quiz: feline Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language