/ Dictionary / Index M milligram: Meaning and Definition of Find definitions for: mil•li•gram Pronunciation: (mil'i-gram"), [key] — n. a unit of mass or weight equal to one thousandth of a gram, and equivalent to 0.0154 grain. Abbr.: mg Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: milligram (Thesaurus) milligal milligram-hour Related Content Daily Word Quiz: frugal Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language