Diameter definition

dī-ămĭ-tər
Diameter is defined as the length of a straight line through the center of a circle.

An example of a diameter is the length of a line sliced down the center of a pie.

noun
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A line segment passing through the center of a circle, sphere, etc. from one side to the other.
noun
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The length of such a segment; width or thickness of a circular or spherical figure or object.
noun
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(geometry) The maximum distance between any two points in a metric space.
noun
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3
The length of such a line segment.
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(geometry) The length of such a line.
noun
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1
A unit of magnification equal to the number of times an object's linear dimensions is increased by the magnifying apparatus.
noun
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1
The length of such a segment.
noun
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1
(geometry) Any straight line between two points on the circumference of a circle that passes through the centre/center of the circle.
noun
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1
A straight line segment passing through the center of a figure, especially of a circle or sphere, and terminating at the periphery.
noun
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(graph theory) The maximum eccentricity over all vertices in a graph.
noun
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Thickness or width.
noun
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A straight line segment that passes through the center of a circle or sphere from one side to the other.
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(optics) The unit of measure of the magnifying power of a lens.
noun
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Alternative Forms

Alternative Form of diameter - diametre

Other Word Forms

Noun

Singular:
diameter
Plural:
diameters

Origin of diameter

  • Middle English diametre from Old French from Latin diametrus from Greek diametros (grammē) diagonal (line) dia- dia- metron measure mē-2 in Indo-European roots

    From American Heritage Dictionary of the English Language, 5th Edition

  • From Old French diametre (French diamètre), from Latin diametrus, from Ancient Greek διάμετρος (diametros) (γραμμή (grammē)) (diametros grammē, “line measuring across”), from διά (dia, “across”) + μέτρον (metron, “measure”).

    From Wiktionary