sphinc·ter /ˈsfɪŋktə $ -ər/ noun [countableC] medical
HBHa muscle that surrounds an opening in your body, and can become tight in order to close the opening 括约肌
Examples from the Corpus
sphincter• the anal sphincter• The sphincters become leaky, and the urine overflows.• Thus it should not be assumed that older patients with ulcerative colitis have weaker sphincters than younger patients.
Originsphincter
(1500-1600)Late LatinGreek, from sphingein“to tie tightly”