define entasis
entasis enÂ·taÂ·sis (Änâ²tÉ-sÄ­s) n. pl. enÂ·taÂ·ses (-sÄzâ²) A slight convexity or swelling, as in the shaft of a column, conventionally employed especially in classical architecture. [Latin, from Greek, tension, from enteinein, to stretch tight : en-, intensive pref.; see en-2 + teinein, to stretch; see ten- in Indo-European roots.] 1  American HeritageÂ® Dictionary of the English Language, Fifth Edition. Copyright Â© 2016 by Houghton Mifflin Harcourt Publishing Company.