Definition of diameter in English:

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Pronunciation: /dʌɪˈamɪtə/


1A straight line passing from side to side through the centre of a body or figure, especially a circle or sphere.
Example sentences
  • The sine wave through the diameter of the circle is the ideal and basic pulse wave.
  • In book one the relations satisfied by the diameters and tangents of conics are studied while in book two Apollonius investigates how hyperbolas are related to their asymptotes, and he also studies how to draw tangents to given conics.
  • The circle with diameter BC intersects the sides AB and AC at M and N respectively.
1.1A transverse measurement of something; width or thickness.
Example sentences
  • Furthermore, none of the particles may have a diameter greater than the thickness of the uncured fluid layer.
  • The first dorsal fin has four rays, the lips are smooth and are roughly the same thickness as the diameter of the eye.
  • The correct length of a buttonhole is determined by the diameter, thickness and type of button used.
breadth, width, depth, thickness;
calibre, bore, gauge;
size, extent
2A unit of linear measurement of magnifying power.
Example sentences
  • In the photograph above, for instance, eggs from the Central American stick-insect genus Bacteria are shown, magnified roughly fifteen diameters; the brown, knobby protruberances are the capitula.
  • Using a micrometer to measure the field diameter of the microscope is recommended.
  • A large aperture eyepiece will increase the filed of view and a large diameter, well coated objective lens will enhance brightness issue.



Pronunciation: /dʌɪˈamɪtrəl/
Example sentences
  • When diametral section planes were selected, second antibody treatment resulted in a 1.5-to 2-fold increase of median fluorescence aggregation index, as summarized in Table 3.
  • All the tested materials presented an increase in diametral tensile strength during the experiment.
  • However, axial and diametral testing of mixes yield different estimates of their resilient stiffnesses.


Late Middle English: from Old French diametre, via Latin from Greek diametros (grammē) '(line) measuring across', from dia 'across' + metron 'measure'.

  • dialogue from Middle English:

    This comes via Old French and Latin from Greek dialogos, from dialegesthai ‘converse with, speak alternately’: the formative elements are dia- ‘through, across’ and legein ‘speak’. The tendency in English is to confine the sense to a conversation between two people, perhaps by associating the prefix dia- with di-. Dia- is also found in diameter (Late Middle English) ‘the measure across’; diaphanous (early 17th century) ‘shows through’; diaphragm (Late Middle English) a barrier that is literally a ‘fence through’, and diaspora (late 19th century) a scattering across.

Words that rhyme with diameter

heptameter, hexameter, parameter, pentameter, tetrameter

For editors and proofreaders

Line breaks: diam|eter

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