/ Dictionary / Index A aniseikonia: Meaning and Definition of Find definitions for: an•is•ei•ko•ni•a Pronunciation: (an"u-sī-kō'nē-u), [key] — n. Ophthalm. a defect of vision in which the images at the retinas are unequal in size. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: aniseikonia (Thesaurus) aniseed anisette Related Content Daily Word Quiz: careening Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language