miosis Meaning, Definition & Usage

1. noun (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)
   reduction division; meiosis.
   
2. noun reflex contraction of the sphincter muscle of the iris in response to a bright light (or certain drugs) causing the pupil to become smaller
   myosis; pupillary reflex; light reflex.
   

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