Words / B2

dy-AM-it-uh/daɪˈæmɪtə/

A diameter is a straight line through the centre of a circle or sphere, or the length of that line: the diameter of; diameter in millimetres. Radius is half of it (a classic twin); circumference is the distance around. Give the diameter in millimetres, showing the working. Mix-up: diameter vs perimeter; diagram; do not write diameter for any width that does not pass through the centre.

Meaning

A straight line through the centre of a circle or sphere, or the length of that line.

Examples

• “Give the diameter in millimetres, showing the working, the maths paper said.”
• “The pipe diameter featured in the DT spec, which is the engineering sense — still name the millimetres.”

Good to know

the diameter of a circle / sphere / pipe; diameter = 2 × radius. Twin: radius. Related: circumference. Trap: perimeter / diagram. Maths, physics, and DT. A line through the centre — show the working.

Near in meaning

radius, width, calibre

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