protractor

UK/pɹəˈtɹæktə(ɹ)/US/pɹəˈtɹæktə(ɹ)/

nounB1+Rare in speech; mostly a word you read · #14,535 of 15,258neutral

Other forms: protractors

A protractor is the half-circle tool for measuring angles in geometry. Use a protractor, line up the protractor, a plastic protractor.

It carries two scales running opposite ways so it can be read from either side, and reading the wrong one is the classic error — check whether your angle is more or less than a right angle before you write the number down.

Definitions of protractor

1nounprotractorA half-circle tool for measuring angles.B1+
“Use a protractor to measure each angle of the triangle.”

protractor is an instrument.

Where it comes from

Proto-Indo-European
*per-
Latin
prōtrahō
English
protract
English, today
protractor

From protract + -or. protract comes from the past participle stem of Latin prōtrahō. by surface analysis, en + pro + tract.

Etymology from Wiktionary, CC BY-SA

Practised in School & Learning, Tools & DIY

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protractor in the wild

Using a protractor, draw a line from either landmark to intersect the 90 degree line off the baseline at the observed angle.
Position circle
The other common types of head are the protractor head, and the centre finder head.
Combination square
The protractor is a commonly used type in the fields of mechanics, engineering, and geometry.
Goniometer
A rolling ruler can draw straight, parallel lines, and also has other instruments included, enabling it to do the jobs of a protractor and compass.
Rolling ruler
The modern rolling ruler, with protractor, pivot pin and multiple pin holes serving as fixed length compasses has been patented in the US in 1991 by Wei Wang.
Rolling ruler

From Wikipedia, CC BY-SA 4.0. These sentences were written by other people about their own subjects; they are here to show the word at work, not as anybody’s opinion.

Related words

the prōtrahō family

portrait

protractor — used about once every 54,060 pages · #14,535 · point at the bar for the others

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