Meaning & use
protractor
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Meaning
nouncountable
A flat instrument, usually shaped like half a circle and marked with degrees, used to measure or draw angles.
Grammar: A countable noun: a protractor, two protractors.
Patterns
- measure an angle with a protractor
- use a protractor
Place the protractor on the line and read the angle.
The student forgot her protractor for the geometry test.
He used a plastic protractor to draw a sixty-degree angle.
Word forms
| plural | protractors |
|---|
Common combinations
- use a protractor
- You need to use a protractor to measure this angle.
- measure with a protractor
- Measure the corner with a protractor and write down the result.
- protractor and ruler
- Bring a protractor and ruler to the maths exam.
- plastic protractor
- A clear plastic protractor lets you see the lines underneath.
- semicircular protractor
- The semicircular protractor covers one hundred and eighty degrees.
Synonyms and how they differ
- angle measurer
- This is a plain description rather than the standard name, and it is rarely used in lessons.
- goniometer
- Goniometer is a technical term for a more precise angle-measuring device used in science and medicine, whereas a protractor is the simple school tool.
Word family
- protract verb
- to make something last longer than necessary
- protracted adjective
- lasting a long time
- protraction noun
- the act of extending something in time or length
Commonly confused: protractor or compass? protractor or tractor?
protractor vs compass
A compass draws circles and arcs, while a protractor measures angles. Do not confuse either with a navigational compass that shows direction.
protractor vs tractor
A tractor is a farm vehicle. Protractor only looks similar because of its ending.
Practice
Which tool would you use to measure the size of an angle?
Choose one answer.
A protractor is marked in degrees and measures angles. A compass draws circles, and a ruler measures straight length.
Make it your own
Write a sentence using “protractor”, then check it and compare it with the examples above.