Definition

A straight line that goes from one side of a circle or sphere to the other side, passing through the center.

Example

The diameter of the circle is twice the length of its radius.

Conversation

Do you remember how we calculated the diameter of that circle in class?

Yeah, I think we just measured across the center, right?

Exactly! It's interesting how the diameter relates to the circumference too.

Absolutely! It makes geometry a lot more fun when you see those connections.

Synonyms & Antonyms

Root Explanation

Diameter → It is formed from "dia-" (meaning through or across) and "metron" (meaning measure). The word "diameter" refers to the measurement across a circle, passing through its center.

Memory Tip

Think of measuring something "across" ('dia-') — that's why diameter means the measurement across a circle.

Visually Confused Words