fiend
feend
- n a cruel wicked and inhuman person
- n an evil supernatural being
- n a person motivated by irrational enthusiasm (as for a cause)
- If you're a fiend for the latest gadget, by all means, get one of these.
- He practiced like a fiend, focusing on the keys the way other children his age focused on a scoop of ice cream.
- In Rumania one may refer to Prince Nicholas, weak-chinned younger son of Dowager Queen Marie, as a? "bully, scandal monger and speed-fiend," but it will cost one just four months.