/ Dictionary / Index N nystagmus: Meaning and Definition of Find definitions for: nys•tag•mus Pronunciation: (ni-stag'mus), [key] — n. a congenital or acquired persistent, rapid, involuntary, and oscillatory movement of the eyeball, usually from side to side. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: nystagmus (Thesaurus) NYSE nystatin Related Content Daily Word Quiz: spectral Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language