[ 'ɪsθməs , 'ɪstməs , 'ɪsməs ]
■ noun
1》 ( plural ~es ) a narrow strip of land with sea on either side, linking two larger areas of land.
2》 ( plural isthmi ) Anatomy a narrow organ or other part connecting two larger parts.
Origin
C16: via L. from Gk isthmos .