/ Dictionary / Index M microseism: Meaning and Definition of Find definitions for: mi•cro•seism Pronunciation: (mī'kru-sī"zum, -sum), [key] — n. Geol. a feeble, recurrent vibration of the ground recorded by seismographs and believed to be due to an earthquake or a storm at sea. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: microseism (Thesaurus) microsegment microsleep Related Content Daily Word Quiz: gregarious Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language