from The American Heritage® Dictionary of the English Language, 4th Edition
- n. Prolonged abnormal dilatation of the pupil of the eye caused by disease or a drug.
from Wiktionary, Creative Commons Attribution/Share-Alike License
- n. The condition of having abnormally large and dilated pupils due to disease or drugs, particularly stimulants such as (meth)amphetamines, cocaine, etc.
from the GNU version of the Collaborative International Dictionary of English
- n. A long-continued or excessive dilatation of the pupil of the eye.
from The Century Dictionary and Cyclopedia
- n. In medicine, a morbid dilatation of the pupil of the eye.
- n. Hydrophthalmia.
from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
- n. reflex pupillary dilation as a muscle pulls the iris outward; occurs in response to a decrease in light or certain drugs
Latin, from Greek mudriāsis.(American Heritage® Dictionary of the English Language, Fourth Edition)
From Latin mydriasis, from Ancient Greek μυδρίασις (mydriāsis, "undue enlargement of the pupil"), from μύδρος (mydros, "mass of red hot material in a forge"), possibly because the pupil is particularly bright or sparkling when dilated. (Wiktionary)