Interminably
'interminably' is the definition.
(synonyms)
This is the entire clue.
(Other definitions for endlessly that I've seen before include "in perpetuity" , "forever?" , "Ceaselessly" , "all the time" , "Ad infinitum" .)
'interminably' is the definition.
(I've seen this in another clue)
This is all the clue.