entasis

American  

[en-tuh-sis] / ˈɛn tə sɪs /

noun

Architecture.

1. a slight convexity given to a column or tower, as to correct an optical illusion.

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entasis British  

/ ˈɛntəsɪs /

noun

1. a slightly convex curve given to the shaft of a column, pier, or similar structure, to correct the illusion of concavity produced by a straight shaft

2. Also called: entasia.  physiol an involuntary or spasmodic muscular contraction

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Etymology

Origin of entasis

1745–55; < Greek, equivalent to enta- (variant stem of enteínein to stretch tight, equivalent to en- en- ² + teínein to stretch) + -sis -sis

Example Sentences

The ancient Greeks made their columns bulge out slightly about a third of the way up to correct for the optical illusion of concavity — a technique known as entasis.

From Washington Post

Observe that the entasis is so slight that the lowest diameter of the shaft is always the greatest diameter.

From A History of Greek Art by Tarbell, Frank Bigelow

This outward curvature of the profile is termed an entasis and in the Parthenon column, which is thirty-four feet in height, amounted to about three-fourths of an inch.

From Visual Illusions Their Causes, Characteristics and Applications by Luckiesh, Matthew

The entasis as given by Fra Giocondo in the edition of 1511.

From The Ten Books on Architecture by Vitruvius Pollio

The entasis of columns and curvature of what would ordinarily be straight lines is familiar to all students of architecture.

From The Brochure Series of Architectural Illustration, Volume 01, No. 08, August 1895 Fragments of Greek Detail by Various