The word empollie appeared in the untranslated phrase á rike empollie in rough notes from the 1960s (PE17/167). Christopher Gilson suggested this was likely an early attempt by Tolkien to define the Quenya expression for “try harder”, elsewhere given as ā rike am(a)ríkie which more literally means “try [with] more trying” (PE17/94). The later phrase involves an intensified noun/adverbial form of the verb ric- “to try”, and it seems likely that empollie is a similar intensified form of pol- “to be [physically] able to”. If so, it probably means something like “*with more effort”.

Neo-Quenya: This word has some pecularities given its abnormal noun/adverb form pollië rather than the expected polië or pólië, and an abnormal intensive[?] prefix em- rather than an- or am- [before p]. As such, I would avoid it in the sense “harder” for purposes of Neo-Quenya, using the á ricë amrícië construction instead; see that entry for discussion.

However, I think it is worth salvaging this word as a noun ᴺQ. ampollië meaning “great effort, struggle”, using the more regular intensive prefix am-.