• 01.083 of Bag-End, Under-Hill, again.
• 12.068 was to be brought back all the way to Bag-End Under-Hill.
• 19.036 of Bag-End, Underhill, Hobbiton.

It is a word, albeit rare, in OED, meaning “small hill”.

“ˈunder-hill, n.” OED Online, Oxford University Press, June 2017, http://www.oed.com/view/Entry/211729. Accessed 21 September 2017.