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Definition of diameter

diameter

/daɪˈæm.ə.tɚ/
di · am · e · ter
Adverb:diametrally
•
Plural:diameters
•
Adjective:diametral
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diameter Lexical Profile

diameter Game Scores & Validity

• noun

1

A straight line passing from side to side through the center of a circle, sphere, or other geometric body, or the length of such a line.

Example

"The ancient oak tree had a trunk measuring over two meters in diameter."

2

A unit of linear measurement of magnifying power, equal to the number of times the linear dimensions of an object are increased by a lens or telescope.

Example

"The laboratory microscope can magnify the cellular specimen by five hundred diameters."

Synonyms
View all synonyms for diameter

Word Nuance & Usage

Do not confuse 'diameter' with 'radius' or 'circumference'; the diameter spans all the way across a circle through its center (twice the radius), whereas the circumference is the distance around its outer edge.

• Rhymes for diameter

• Nearby Words

dialogue
dialysis
diamantina
diameter
diametric
diametrical
diametrically

Word Origin & Etymology

Borrowed in Middle English via Old French and Late Latin from Ancient Greek 'diametros' (meaning 'diagonal of a circle'), formed from 'dia-' (across, through) and 'metron' (a measure).

Cite this Entry

Wordmom. (2026). Definition of Diameter. In Wordmom Dictionary. Retrieved Nov 5, 2026, from https://wordmom.com/dictionary/diameter
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