Reflex contraction of the sphincter muscle of the iris in response to a bright light (or certain drugs) causing the pupil to become smaller

• Constriction of the eye's pupil
• (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)
• Excessive pupil constriction
• Reproductive cell division
• Constriction of the pupil
• Constriction of pupils

Wikipedia Word definitions in Wikipedia
Miosis or myosis , /maɪˈoʊ sɪs/, from Ancient Greek μύειν, mūein , "to close the eyes", is a term with various definitions, which generally include constriction of the pupil . The opposite condition, mydriasis , is the dilation of the pupil . Anisocoria ...

WordNet Word definitions in WordNet
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) [syn: meiosis , reduction ...

Wiktionary Word definitions in Wiktionary
n. Contraction of the pupil of the eye.