Fel

According to the Old English Dictionary:

felo, fæle;

FEL

adj. FELL, cruel, savage; crūdēlis, sævus. [Wyc. fel, felli crafty: Piers P. fell fierce: Chauc. felle strong, fierce: Laym. felle, pl. cruel: Scot. fell keen, hot, acute: O. Frs. fal: Dut. Kil. fel violent: O. Fr. fel cruel, wicked: Ital. fello wicked: Ir. feal bad, naughty, evil.] DER. æl-fæle, eal-felo, wæl-fel. fel