開口部

(1)an aperture or hole that opens into a bodily cavity; "the orifice into the aorta from the lower left chamber of the heart"

(2)身体の腔に通じる孔あるいは穴

(3)an man-made opening; usually small

(4)人工物の穴

(5)通常小さい

(6)a natural opening in something

(7)開口部