quintilionèsim

From quintilió (“billion”) + -èsim (“ordinal suffix”)

quintilionèsim (feminine quintilionèsima, masculine plural quintilionèsims, feminine plural quintilionèsimes)

1. quintillionth (long scale) ; nonillionth (short scale)

For most fractional numbers, the ordinal number is used to indicate the denominator of the fraction. The ordinal quintilionèsim is used to indicate this denominator just as the corresponding English ordinal would be. Exceptions to this rule include mig (“half”), terç (“third”), quarter (“quarter”), milionèsim (“millionth”), bilionèsim (“billionth”), ....

The feminine form of the ordinal is usually used as the collective noun for a set of like objects of that size. Exceptions to the usual rule include parell (“set of 2”), qüern (“set of 4”), centenar (“set of 100”), grossa (“set of 144”), miler (“set of 1000”), and milenar (“1000”).