entasis

noun

en·​ta·​sis ˈen-tə-sis 

plural entases ˈen-tə-ˌsēz 

: a slight convexity especially in the shaft of a column

Word History

Etymology

Greek, literally, distension, stretching, from enteinen to stretch tight, from en- en- entry 2 + teinein to stretch — more at thin

First Known Use

1664, in the meaning defined above