'miosis' definitions:

(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, miosis, reduction division]

Reflex contraction of the sphincter muscle of the iris in response to a bright light (or certain drugs) causing the pupil to become smaller [syn: light reflex, pupillary reflex, miosis, myosis]