diameter

Universal Words 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 compareRADIUS: the diameter of a tree trunk * The dome is 42.3 metres in diameter. 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).