1. Relating to an unspecified ordinal number: ten to the nth power.
2. Highest; utmost: delighted to the nth degree.

[N², indefinite number + -TH³.]

The American Heritage® Dictionary of the English Language, Fourth Edition Copyright © 2007, 2000 by Houghton Mifflin Company. Updated in 2009. Published by Houghton Mifflin Company. All rights reserved.