American English

Definition of diameter noun from the Oxford Advanced American Dictionary



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  1. 1a straight line going from one side of a circle or any other round object to the other side, passing through the center the diameter of a tree trunk The dome is 120 feet in diameter. compare radius
  2. 2(technology) a measurement of the power of an instrument to magnify something a lens magnifying 300 diameters (= making something look 300 times larger than it really is).
See the Oxford Advanced Learner's Dictionary entry: diameter