nth
adjective /enθ/
  /enθ/
[only before noun] (informal)Idioms - used when you are stating that something is the last in a long series and emphasizing how often something has happened
- It's the nth time I've explained it to you.
 
 
Idioms 
to the nth degree 
- extremely; to an extreme degree
- The children tested her patience to the nth degree.