/ Dictionary / Index M msec: Meaning and Definition of Find definitions for: msec Pronunciation: [key] millisecond; milliseconds. m/sec Pronunciation: [key] meter per second; meters per second. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: msec (Thesaurus) M.S.E. M.S.Ed. Related Content Daily Word Quiz: hedonist Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language