Diameter: Definition, Examples, and Usage

Meaning 1：line through center (diameter)

diameter 🔊

/daɪˈæmɪtər/

a straight line through the center of a circle, from one side to the other.

Diameter of a pizza measured with a ruler through center

line through center 🔊

➕

/laɪn θruː ˈsɛntər/

A straight line segment that passes through the center of a circle or sphere, connecting two points on its boundary.

📁 Category：Objects & Materials 🔖 Level：intermediate

📘 Details & Usage

📖 Root Explanation

From Greek 'dia' (across) + 'metron' (measure).

💡 Mnemonic

Dia (across) + meter (measure) = measure across the center.

📖 Example

The recipe says the cake tin should have a diameter of 20 centimeters. 🔊 The recipe says the cake tin should have a diameter of 20 centimeters.

🔗 Collocations

outer diameter – the external diameter of a tube or cylinder

diameter of a circle – the measurement across a circle through its center

measure the diameter – to determine the length of the diameter

🔄 Synonyms

caliber (n.) – the internal diameter of a gun barrel or tube

width (n.) – the measurement from side to side, often used informally for diameter

breadth (n.) – the distance across something, similar to diameter in certain contexts

🌱 Derivatives

diametrical (adj.) – relating to or along a diameter

diametrically (adv.) – in a diametrical manner; completely opposite

📖 Cultural Story

First used in geometry by Euclid (c. 300 BC) to describe the line that measures a circle across its center. The term entered English via Latin 'diametrus' in the 14th century.