being the last in a series of infinitely decreasing or increasing values, amounts, etc.
(of an item in a series of occurrences, planned events, things used, etc., that is thought of as being infinitely large) being the latest, or most recent:
This is the nth time I’ve told you to eat slowly.
the nth degree / power,
(maths) of or representing an unspecified ordinal number, usually the greatest in a series of values: the nth power
(informal) being the last, most recent, or most extreme of a long series: for the nth time, eat your lunch!
(informal) to the nth degree, to the utmost extreme; as much as possible
1852, in phrase to the nth, figurative use of a mathematical term indicating indefinite number, in which n is an abbreviation for number (n.).
see: to the nth degree
1. National Telecommunications and Information Administration. National Telecommunications and Information Administration
National Technical Institute for the Deaf