While looking for the origin of the the suffix of terms like underneath and beneath I’ve found that it derives from “neoðan "below, down, from below," from Proto-Germanic niþar "lower, farther down, down" from which the current term “nether”
“Nether” appears to be an uncommon term, but dictionaries seem to contradict each other about its usage:
Collins Dictionary describe “nether” as “old fashioned”,
Cambridge Dictionary defines its usage as “humorous”, while
M-W doesn’t mention any specific issue and shows a number of current usage examples.
Google Books appears to suggest that the term usage is not significantly lower than a century ago, so what is the exact current usage of “nether”?
Is it just literary or formal? Does it have humorous connotations? Is it actually old-fashioned as suggested above?