noun
round window; fenestra rotunda
Anatomical term for the membrane-covered opening between the middle ear and the cochlea. Used in medical and biological contexts.
正円窓は内耳への振動伝達に関与する。
The round window is involved in transmitting vibrations to the inner ear.
卵円窓 (oval window) is another membrane-covered opening in the inner ear, located above the round window and connected to the stapes.
From 正円 (perfect circle) + 窓 (window), a calque of the Latin 'fenestra rotunda'.