| Word | Definitions | Synonyms |
|---|---|---|
| fiend | (noun) a cruel wicked and inhuman person | Synonyms: demon, devil, monster, ogre |
| (noun) a person motivated by irrational enthusiasm (as for a cause) | Synonyms: fanatic | |
| (noun) an evil supernatural being | Synonyms: daemon, daimon, demon, devil | |
| fiendish | (adjective) extremely evil or cruel; expressive of cruelty or befitting hell | Synonyms: demonic, diabolic, diabolical, hellish, infernal, satanic, unholy |
| fiendishly | (adverb) as a devil; in an evil manner | Synonyms: devilishly, diabolically |