From Proto-Italic *pikos, from Proto-Indo-European *(s)peyk- (“woodpecker; magpie”), whence also Latin pīca (“magpie”).
Romance evidence points to a form with -cc-, perhaps onomatopoeic and/or influenced by Vulgar Latin *pīccāre (“to strike, sting, peck”) and/or Proto-Germanic *pikkōną (“to pick, peck, prick”). Cf. Vulgar Latin *pīcca (“pick-axe”).
Cognate with Umbrian peico (acc.sg.), Sanskrit पिक (piká, “cuckoo”), German Specht (“woodpecker”), Swedish spett (“crowbar, skewer; kind of woodpecker”).