diam·eter [diameterdiameters] BrE [daɪˈæmɪtə(r)] NAmE [daɪˈæmɪtər] noun 1. a straight line going from one side of a circle or any other round object to the other side, passing through the centre •the diameter of a tree trunk •The dome is 42.3 metres in diameter. compare ↑radius 2. (technical)a measurement of the power of an instrument to ↑magnify sth •a lens magnifying 300 diameters (= making sth look 300 times larger than it really is)
Word Origin: late Middle English: from Old French diametre, via Latin from Greek diametros (grammē) ‘(line) measuring across’, from dia ‘across’ + metron ‘measure’.
Example Bank: •The mirror is 25cm in diameter. •The tubes have an internal diameter of 2 mm. •a method of calculating the diameter of the earth •The diameter of the tree trunk was more than a metre. •The dome is 42.3 metres in diameter. •The radius of a circle is half its diameter.
