/ Dictionary / Index M milligram-hour: Meaning and Definition of Find definitions for: mil•li•gram-hour Pronunciation: (mil'i-gram"our", -ou"ur), [key] — n. Radiotherapy. a unit of measure for a dose of radium expressed as the amount of radiation received by exposure to one milligram of radium for one hour. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. milligram millihenry 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