Anatomical term for the opening in the center of the iris. In everyday conversation, ひとみ is more common.
医者は瞳孔の大きさを調べた。
The doctor checked the size of the pupil.
In the dark, the pupil dilates.
leukocoria; white pupil
pupillary reflex
pupil dilation; mydriasis
pupil constriction; miosis
sphincter muscle of the pupil; sphincter pupillae
Sino-Japanese word from 瞳 (pupil) and 孔 (hole, opening).