Usually explained as a derivation from the words for "fist" and "finger":
- Proto-Indo-European *pn̥kʷ-sti-s (“fist”) > Proto-Germanic *funhstiz > *funstiz (> Old English fȳst (“fist”), Old Frisian fest (“fist”), Old High German fūst (“fist”))
- Proto-Indo-European *penkʷ-ró-s (“finger”) > Proto-Germanic *fingraz (“finger”) (> Gothic 𐍆𐌹𐌲𐌲𐍂𐍃 (figgrs, “finger”), Old Norse fingr, Old English finger, Old High German finger)
Ultimately all of these forms may go back to a verbal stem *penkʷ- (“to take in hand, to handle”), but which is not attested in any of the daughter languages. According to Blažek (1999: 229) however, the meanings “fist”, etc. are primary. Relation has been suggested to *ponkʷ-to- (“all, whole”), seen in Latin cūnctus and Hittite [script needed] (pa-an-ku-uš, “family”), thus *pénkʷe meaning "the whole (hand)".
Note the existence of an Italo-Celtic variant *kʷoinkʷe, which gave raise to the Latin quīnque (descent from *pénkʷe would have yielded **quenque), Welsh pump (the variant pymp being the regular descendant of *pénkʷe) and Old Irish cóic.
- Luwian: [script needed] (paⁿta)
- Celtic: *kʷinkʷe (see there for further descendants)
- Germanic: *fimf (see there for further descendants)
- Hellenic: *pénkʷe (see there for further descendants)
- Indo-Iranian: *pánča (see there for further descendants)
- Messapic: [script needed] (penka-)
- Phrygian: πινκε (pinke)
- Blažek, Václav. 1999. Numerals. Comparative-Etymological Analysis and their Implications. Brno: Masarykova Univerzita v Brně