Emily Dickinson Lexicon

monster (-'s), n. [OFr mostre 'disfigured person, misshapen being'.]

1. Person, being, or inanimate object extremely wicked, cruel, or inhumane by nature to other things or people, sometimes to the point of utter destruction; person of savage and relentless appearance.
2. Evil force or power causing trepidation or fear.
3. [Fig.] huge burden; mountain one must overcome to progress.