Borrowed from Doric Greek πᾶνος (pânos, “thread on the bobbin; bobbin”) (which equals Attic Greek πῆνος (pênos); more commonly attested in the diminutive πᾱνίον (pāníon) / πηνίον (pēníon)). More at πήνη (pḗnē). The non-bobbin meanings are likely metaphorical extensions of the bobbin meaning, though some, such as Schrijver and Derksen, have taken the "swelling" meaning as derived from a separate Proto-Indo-European *pnHk- (“swelling, bunch”), connecting the word to Proto-Slavic *pǫ̀čiti (“to swell, burst”), *pǫkъ (“bunch”).