an instrument that measures the circumference of a tyre
2.
an instrument used to record angles and bearings
circumferentor in American English
(sərˈkʌmfəˌrentər)
noun
Surveying
an alidade equipped with a compass and two diametrically opposed vertical arms with slits for sighting through
Word origin
[1600–10; ‹ L circumferent(ia) circumference + -or2]This word is first recorded in the period 1600–10. Other words that entered Englishat around the same time include: alpine, criticism, progressive, quarantine, umbrella