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

  • n. Constriction of the pupil of the eye, resulting from a normal response to an increase in light or caused by certain drugs or pathological conditions.

from Wiktionary, Creative Commons Attribution/Share-Alike License

  • n. Contraction of the pupil of the eye.

from The Century Dictionary and Cyclopedia

  • n. Diminution.
  • n. In cytology, the reduction-process in organisms, including mitapsis (or synapsis) and the subsequent heterotypic and homotypic divisions. This process results in reducing to one half the number of chromosomes in the nuclei. Farmer and Moore. Improperly spelled maiosis.
  • n. Used by error or substitution for myosis.

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

  • n. (genetics) cell division that produces reproductive cells in sexually reproducing organisms; the nucleus divides into four nuclei each containing half the chromosome number (leading to gametes in animals and spores in plants)
  • n. reflex contraction of the sphincter muscle of the iris in response to a bright light (or certain drugs) causing the pupil to become smaller


Greek mūein, to close the eyes + -osis.
(American Heritage® Dictionary of the English Language, Fourth Edition)
From Ancient Greek μύειν (mūein, "to close the eyes") + -osis. (Wiktionary)


  • A lot of new characters and situations to keep up with on Private Practice, as the practices divide like miosis.

    He Never Saw It Coming : Bev Vincent

  • Lomb Inc. The drug has two-thirds of the U.S. sales for the class of prescription drugs used to induce miosis, or constriction of the pupil.

    China Approves Novartis-Alcon Deal

  • - Diane Carman:Quick: Define miosis and mitosis.

    Archive 2005-08-01

  • Severe miosis and the reduced ability to see in dim light can persist for 48 hours after onset.

    FM 7-98 Appendix F - Uses of Mission-Oriented Protectiive Posture

  • Commanders must identify personnel performing critical tasks dependent on night vision and initiate precautions to minimize miosis:

    FM 7-98 Appendix F - Uses of Mission-Oriented Protectiive Posture

  • They should disperse in the open air and use the buddy system to observe for possible miosis symptoms.

    FM 7-98 Appendix F - Uses of Mission-Oriented Protectiive Posture

  • With the start of regeneration of the oculomotor nerve the Ac.Ch. appears again, but in too small quantities to cause miosis with light stimulus alone, i.e. without the increased activity provided by eserine.

    Otto Loewi - Nobel Lecture

  • Pharmacokinetics and pharmacodynamics were measured through serial blood samples and observations of cold pressor test response, as well as pupillometry to determine opioid-induced miosis of drug effect and exposure over time.

  • The syndrome consists of poor pupillary dilation, progressive intraoperative miosis with billowing of the iris, and increased risk of iris prolapse through the corneal sections.

    Latest headlines from BMJ

  • On maintenance doses of dope, the only sure external signs of intoxication are miosis, or pinpointing of the pupils, and a Lauren

    Chicago Reader


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  • I can see it in your eye.
    How'd you lose the other one by the way?

    January 4, 2012