Nonius

Etymology
, the Latinised form of the name of its inventor, (1502-78), a Portuguese mathematician and geographer.

Noun

 * 1)  nonius
 * 2) vernier caliper

Usage notes
Unlike its English counterpart, the term also encompasses the more sophisticated vernier caliper, which works on a similar principle.

Proper noun

 * 1) a Roman nomen gentile, gens or "family name" famously held by:
 * , a Roman grammarian