fell (v.1)
Old English fællan (Mercian), fyllan (West Saxon) "make fall, cause to fall," also "strike down, demolish, kill," from Proto-Germanic *falljan "strike down, cause to fall" (cognates: Old Frisian falla, Old Saxon fellian, Dutch fellen, Old High German fellen, German fällen, Old Norse fella, Danish fælde), causative of *fallan (source of Old English feallan, see fall (v.)), showing i-mutation. Related: Felled; feller; felling.
fell (adj.)
"cruel," late 13c., from Old French fel "cruel, fierce, vicious," from Medieval Latin fello "villain" (see felon). Phrase at one fell swoop is from "Macbeth."
fell (n.1)
"rocky hill," c.1300, from Old Norse fiall "mountain," from Proto-Germanic *felzam- "rock" (cognates: German Fels "stone, rock"), from PIE root *pel(i)s- "rock, cliff."
fell (v.2)
Old English feoll; past tense of fall (v.).
fell (n.2)
"skin or hide of an animal," Old English fel, from Proto-Germanic *felnam- (cognates: Old Frisian fel, Old Saxon fel, Dutch vel, Old High German fel, German fell, Old Norse fiall, Gothic fill), from PIE *pel-no-, suffixed form of root *pel- (4) "skin, hide" (see film (n.)).