obturator

noun5

1. •
   An object used to obstruct a hole, such as a fissure of the palate.
2. •
   The membrane vessels, etc. that close the obturator foramen, or thyroid foramen, a large opening or fenestra in the anterior part of the hip bone.
3. •
   A valve closure member (disk, gate, plug, etc.).

   • Obturators, held down by compressed air, close the pipe giving direct access from the h.p. exhaust to the l.p. steam chest, and so prevent compound working; […]. — 1952
4. •
   Any device for preventing the escape of gas through the breech mechanism of a breech-loading gun; a gas check.
5. •
   A camera shutter.