1. Satan; the devil.
2. any evil spirit; demon.
3. a diabolically cruel or wicked person.
4. a person or thing that causes mischief or annoyance.
5. Informal. a person who is extremely addicted to some pernicious habit: a baking fiend.
6. Informal. a person who is excessively interested in some game, sport, etc.; fan; buff.
7. a person who is highly skilled or gifted in something: a fiend at baking...O_o
I'm contactable at firstname.lastname@example.org