Sphincter

[Sarah]

A muscle which surrounds, and by its contraction tends toclose, a natural opening; as, the sphincter of the bladder.

[Sarah]

ring-like muscle found in the anus

[Sarah]

noun: one's pooper

[Sarah]

the muscle that makes you poo

[Sarah]

the circular muscle in your arse;
the poo-cutter

[Sarah]

possibly the coolest word in the english language
may hurt during anal penetration

[Sarah]

muscle in ur bumhole that acts like a railroad switch tie to direct the output

[Sarah]

ring of muscle on [crevis]

[Sarah]

That's your butt hole.

[Justin Bieber]

A ring of muscle surrounding and serving to guard or close an opening or tube, such as the anus or the openings of the stomach.