The definition of a shark is ….
1. a long-bodied chiefly marine fish with a cartilaginous skeleton, a prominent dorsal fin, and toothlike scales. Most sharks are predatory, although the largest kinds feed on plankton, and some can grow to a large size.
2 a small SE Asian freshwater fish with a tail resembling that of a shark, popular in aquaria.
The definition of a demon is ….
1. an evil spirit or devil, especially one thought to possess a person or act as a tormentor in hell. “he was possessed by an evil demon”
2. a forceful or skilful performer of a specified activity.”a friend of mine is a demon cook”