/ Dictionary / Index M midstream: Meaning and Definition of Find definitions for: mid•stream Pronunciation: (mid'strēm'), [key] — n. the middle of a stream. the middle period of a process, course, or the like. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: midstream (Thesaurus) midst midsummer Related Content Daily Word Quiz: vertigo Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language