nonius

/ˈnəʊnɪəs/

Etymology

Borrowed from Latin Nonius, the Latinised form of the name of its inventor, Pedro Nunes (1502-78), a Portuguese mathematician and geographer.

noun

  1. A device for adjusting the accuracy of mathematical instruments, later superseded by the vernier.“Well, of course, one must manipulate the various Screw-Settings precisely, read the Nonius, and an hundred other details besides I’d but bore you with,—”