Meaning of diameter in English:


Pronunciation /dʌɪˈamɪtə/

See synonyms for diameter

Translate diameter into Spanish


  • 1A straight line passing from side to side through the centre of a body or figure, especially a circle or sphere.

    ‘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.’
    • ‘One day at school we were told that if AB is a diameter of a circle, and C is any point on the circumference, then the angle ACB is a right angle.’
    • ‘And this he proved by first showing that the squares on the diameters have the same ratio as the circles.’
    • ‘We owe to him a note on the curvature of elastic rods, several works on the flow of air, and finally, in 1848, an important posthumous note on the rectilinear diameters of curves.’
    • ‘He wrote further articles on cubic curves and in this area he wrote the memoir On the diameters of cubic curves which was published in the Transactions of the Royal Society in 1889.’
    • ‘Also, the ortholine serves as the common radical axis of the three circles constructed on the diagonals as diameters, such that whenever the circles intersect, all three of them intersect in two points on the ortholine.’
    • ‘Users can measure the distance of vertices/edges/faces, the angle of edges/faces, and the radii and diameters of circles.’
    • ‘Can we draw a line thinner than the diameter of a hydrogen atom?’
    • ‘Given a circle, find a point outside the circle where the tangent to the circle and diameter produced, have a given ratio.’
    • ‘He was the first to resolve Kepler's Problem on cutting a semicircle in a given ratio by a line through a given point on its diameter.’
    • ‘Therefore, all diameters of a centrally symmetric shape of constant width pass through the center of symmetry.’
    • ‘In 30 feet of water the circle has a diameter of 3 feet.’
    • ‘The diameter of a sphere is 6.25 nm, and panicles cannot be closer than that.’
    • ‘The dimensions also suggest that the intact liposome as a sphere should have a diameter of several hundred nanometers.’
    • ‘In order to accomplish this end, the diestro must move off the diameter of the circle and place himself at an angle to his adversary.’
    • ‘They were represented by red circles having a diameter of 5 mm presented on a black screen.’
    • ‘The distance from the ground to the tip of his extended index finger is the diameter of the circle.’
    • ‘The rule is to cut 1/9 off the circle's diameter and to construct a square on the remainder.’
    1. 1.1A transverse measurement of something; width or thickness.
      ‘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.’
      • ‘Linzon carefully observed the condition of the bark and other parts of the trees, measured their diameters and took bore samples to measure tree rings.’
      • ‘In contrast, algal cells tend to be similar in size, so the diameter of a clump of algal cells would depend on the number of cells in the cluster.’
      • ‘Objects from 1 to 10 cm in size - about the diameter of a salad bowl - cause the real worry.’
      • ‘The best of these fruits, which range in size from the diameter of a pea to that of a cherry tomato, can compete with blooms for beauty.’
      • ‘They are two to three times the diameter of Earth - the size of Neptune.’
      • ‘Bark thickness and stem diameter were recorded each time a probe was installed or removed.’
      • ‘Prune out all canes with diameters less than a pencil width and old, brown canes that tend to be less productive.’
      • ‘Microscopic examination revealed that the increase of the root diameter was due to an increased thickness of the cortex.’
      • ‘The rosette diameter was measured after full leaf expansion using a ruler with 1 mm precision.’
      • ‘Woody stem diameters were measured with calipers to the nearest millimeter immediately above the root collar.’
      • ‘Estimated leaf mass of first-order branches is plotted against basal stem diameter of the branch in Fig.10.’
      • ‘The fluted barrel would have a larger outside diameter, and thus be stiffer.’
      • ‘"Transco has 280 kilometres of 48 inch diameter pipe in the UK and we have had no problems.’
      • ‘We estimated average tree diameter for canopy and subcanopy trees combined.’
      • ‘Work the screwdriver around to increase the diameter of the hole until it is slightly smaller than the wooden dowel.’
      • ‘Table saw size is specified by the maximum diameter of the blade they will accept.’
      • ‘Flowers are erect, and diameters range from 1.9 to 2.7 cm when tepals are completely expanded.’
      breadth, width, depth, thickness
      View synonyms
  • 2A unit of linear measurement of magnifying power.

    ‘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.’
    • ‘The smaller diameter objective lens is less likely to reflect light.’
    • ‘Customized spacers can be used to fill measured gaps, or the mount diameters can be machined at assembly to closely match the measured diameters of the lenses.’


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