falco.

Uncertain and disputed origin, but probably from Germanic given the early attestation and widespread use of the word in Germanic. Perhaps from Old High German falco, falcho, falucho (“falcon”), from Proto-West Germanic *falkō, from Proto-Germanic *falkô (“falcon", literally, "grey bird”), from Proto-Indo-European *polH-, *pelH- (“grey, bluish”) + *-(u)k-, a suffix found in the names of several types of birds (e.g. *alkǭ, *habukaz, Proto-West Germanic *kranuk, etc.). Cognate with Old Saxon falko (“falcon”), Old English *fealca, fealcen (“falcon”), Old Norse fálki (“falcon”), Old High German falo (“pale”), Latin pullus (“dusky coloured, blackish”). More at fallow. Alternate etymology connects falcō to Latin falx (“sickle, hook”), from Proto-Indo-European *dʰelk-, *dʰelg- (“a cutting tool”) due to the bird's curved beak and talons, but this derivation is usually regarded as folk-etymology.

Etymology tree Latin falx Proto-Indo-European *-h₂ Proto-Indo-European *-éh₂ Proto-Indo-European *-yéti Proto-Indo-European *-eh₂yéti Proto-Indo-European *-h₂tiinflu. Proto-Italic *-ājō Proto-Italic *-āō Latin -ō Latin falcō From falx + -ō.