Interminably is a related term of endlessly.
As adverbs the difference between interminably and endlessly
is that interminably is in an interminable manner while endlessly is in an endless manner; continuously without limit.
interminably
English
Adverb
(-)
in an interminable manner
seemingly endless
endlessly
English
Adverb
(
en adverb)
in an endless manner; continuously without limit
See also
* indefinitely