Miosis

Part of speech: noun

Pronunciation: /maɪˈoʊsɪs/

Definitions

1. The process in which the pupil in the eye becomes smaller due to light exposure or certain medications occurs
2. This narrowing of the eye's pupil can arise from bright light, drugs, or health conditions
3. A physiological response where the opening in the center of the eye reduces size, often reacting to light or substances

Etymology: Miosis is a Greek word built around the idea of closing the eyes. In ancient Greek, "múō" meant "to close the eyes" or "shut the mouth," and it is the source of the word "mýstēs," a person initiated into secret rites, whose eyes and lips were kept closed about what they had learned. The modern term adds the suffix "-osis," a Greek noun ending that names a process or abnormal condition, so the pupil's narrowing was described as a kind of eye-closing. There is a near-twin in English that few people would connect to it. "Meiosis," the cell-division term, comes from a different Greek word, "meíōsis," meaning "diminution" or "lessening," and it is a neighbour in sound and spelling but not in origin. Miosis and meiosis are therefore separate words that happen to look alike on the page, one tied to shutting and the other to shrinking.