An implacable or malicious foe; one who is diabolically wicked or cruel; an infernal being; applied specifically to the devil or a demon. Into this wild abyss the wary fiend Stood on the brink of hell and looked a while. (Milton) O woman! woman! when to ill thy mind Is bent, all hell contains no fouler fiend. (Pope)
Origin: oe. Fend, find, fiend, feond, fiend, foe, as. Feond; akin to os. Fiond, D. Vijand enemy, OHG. Fiant, g. Feind, Icel. Fjand, Sw. & dan. Fiende, goth. Fijands; orig. P.pr. Of a verb meaning to hate, as. Feon, feogan, OHG. Fin, goth. Fijan, Skr. Piy to scorn; prob. Akin to E. Feud a quarrel. 81. Cf. Foe, Friend.