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

Where the spire has no entasis the same effect is produced by the introduction of small projecting gables, bands of carving, or a little coronal of pinnacles.

From Our Homeland Churches and How to Study Them by Heath, Sidney

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 best known correction is the diminution in diameter or taper, and the entasis or convex curve of the tapered outline of the shaft of the column.

From Architecture Classic and Early Christian by Smith, T. Roger (Thomas Roger)

This, the most pleasing of all the renaissance cloisters in Portugal, has four arches on each side resting on fluted columns which though taller than usual in cloisters, have no entasis.

From Portuguese Architecture by Watson, Walter Crum