Definitions

from The American Heritage® Dictionary of the English Language, 4th Edition

  • n. The condition of the normal eye when parallel rays are focused exactly on the retina and vision is perfect.

from Wiktionary, Creative Commons Attribution/Share-Alike License

  • n. The condition of perfect vision, where images are correctly brought to a focus on the retina.

from the GNU version of the Collaborative International Dictionary of English

  • n. That refractive condition of the eye in which the rays of light are all brought accurately and without undue effort to a focus upon the retina; -- opposed to hypermetropia, myopia, and astigmatism.

from The Century Dictionary and Cyclopedia

  • n. Normal power of accommodation, in which the light from a luminous point at any distance from the eye not less than 10 or 12 centimeters (3.9 or 4.7 inches) can be focused to a point on the retina. Also emmetropy.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

  • n. (ophthalmology) the normal refractive condition of the eye in which there is clear focus of light on the retina

Etymologies

Greek emmetros, well-proportioned, fitting (en, in; see en-2 + metron, measure; see meter2) + -opia.
(American Heritage® Dictionary of the English Language, Fourth Edition)

Examples

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  • That is, 20/20 vision.

    July 9, 2008