demon

nouns

an evil supernatural being

daemon, daimon, demon, devil, fiend

is derived from

a cruel wicked and inhuman person

demon, devil, fiend, monster, ogre

is derived from

is derived from

someone extremely diligent or skillful

"he worked like a demon to finish the job on time"; "she's a demon at math"

demon

is a type of (narrower)

a person who acts and gets things done

"he's a principal actor in this affair"; "when you want something done get a doer"; "he's a miracle worker"