1. Like a fiend; malicious.

Nuttall's Standard dictionary of the English language By Nuttall, P.Austin

• findish,
• fiinish,
• fedish,
• feindish,
• finsish,
• fenish,
• fisnish,
• finnish,
• fielfish,
• fendlich,
• diendish,
• ciendish,
• viendish,
• giendish,
• fiendiah,
• fienish,
• fiendsh,
• fiendis,
• fienidsh,
• fienndish

• finish,
• finds,
• finnish,
• fiendishly.

The adjective form of the word "Fiendish" is "Fiendish".

The plural form of "fiendish" is "fiendishes".

The singular form of the word "fiendish" is "fiend"