Definition of protractor in English:



  • 1An instrument for measuring angles, typically in the form of a flat semicircle marked with degrees along the curved edge.

    • ‘Some came armed with T-scales, drawing boards, protractors and compasses.’
    • ‘Get out some graph paper or maybe a protractor because this may get complicated.’
    • ‘Use a protractor to set the fully extended blade at 10 [degrees] off vertical.’
    • ‘In a full analysis, Christina uses a ruler and protractor to measure the letters and angles.’
    • ‘We are pushed into thinking that illusions must be departures from quite simple-minded physics, as measured with rulers, protractors, and clocks.’
    • ‘Holding the protractor at your desired angle, look up the straight edge of the protractor.’
    • ‘Do you need a protractor to measure their angles?’
    • ‘To measure latitude, Frémont had two sextants and a reflecting circle, essentially sophisticated protractors; they were used to measure the angle of the sun or the polestar above the horizon.’
    • ‘A protractor was used to measure the angle of this line to the transverse line and hence the angle to the apex of the nucellus.’
    • ‘Points went over from angles almost off the protractor that day and the pace and accuracy of their play hit a level hardly seen in any other game this year.’
    • ‘‘After developing the prototype with the help of circular protractors, I improvised the model with assistance from professors of engineering colleges,’ he adds.’
    • ‘The angle of pinnation was found by placing a protractor along the central tendon and measuring the angle of an individual fiber to the nearest 0.5 degree.’
    • ‘At Heathrow Airport today, an individual later discovered to be a public school teacher was arrested trying to board a flight while in possession of a compass, a protractor, and a graphical calculator.’
    • ‘Deflection angles of terminal segments relative to the sub-terminal segments were measured to the nearest 2° with a protractor attached to the apparatus after each additional weight was added.’
    • ‘During the interviews, the students had access to additional papers, pens, protractors, and a calculator for any necessary calculations.’
    • ‘Some of the stuff like protractors and compasses I had to design from scratch and I worried about how inaccurate they were.’
    • ‘He was also interested in other measuring devices and took out a patent for a folding protractor, which he patented in 1890.’
    • ‘Lane's descendants were as prudent as he, saving his compass and its tripod, his brass protractor, his surveyor's chain, brass dividers, the wooden globe, and, of course, every scrap he wrote.’
    • ‘Her fingers unzipped the zipper and took out her binder for math along with her calculator, pencil, and protractor.’
    • ‘Accessories for rules are presented in another chapter that describes attachments used with rules such as fences, protractors, gauges, trammels, and carrying cases.’
  • 2Zoology
    A muscle serving to extend a part of the body.

    Compare with retractor
    • ‘In the overhead thrower, the shoulder external rotator muscles, scapular retractor muscles, and protractor and depressor muscles are frequently isolated because of weakness.’
    • ‘It is tempting to hypothesize that because the limb girdles display positive allometry, the protractor and retractor muscles attached to them did as well.’
    • ‘They accomplish this coordination with proprioceptive feedback through the hypoglossal nerve that disinhibits activation of the jaw depressors when the tongue protractor muscle is activated.’
    • ‘Two pairs of epibranchials are present in adults, one bony and one cartilaginous, compared to a single pair in most other families, and the protractor muscle encompasses both epibranchials.’
    • ‘Although all of the protractor and retractor muscles have roles in swing phase, most play little or no role in support phase when dogs trot at steady speed on the level.’