The nucleus divides into four nuclei each containing half the chromosome number (leading to gametes in animals and spores in plants)

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

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 ...

Douglas Harper's Etymology Dictionary Word definitions in Douglas Harper's Etymology Dictionary
1819, from Greek myein "to shut (the eyes)" + -osis . Greek myein is perhaps originally "to close the lips," from PIE *meue- "to be silent" (see mute (adj.)). Related: Miotic .