/ Dictionary / Index M motion sickness: Meaning and Definition of Find definitions for: mo'tion sick"ness Pronunciation: [key] a feeling of nausea and dizziness, sometimes accompanied by vomiting, resulting from stimulation by motion of the semicircular canals of the ear during travel by car, plane, etc. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. motion picture motion study Related Content Daily Word Quiz: wizened Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language