Fistful comes from fist + -ful; fist is from Old English fȳst ('fist'), from Proto-Germanic *fūstiz, from Proto-Indo-European *pn̥kʷstis, perhaps related to *penkʷe ('five'). Morphologically, the account is both compositional and suffixal: -ful marks the visible structure by which the older base becomes the modern form. In present use, it is used as a noun meaning "as much as can be held in one fist; a handful", so the historical material remains connected with the current sense rather than standing as bare ancestry. The wider English family includes related forms such as fist, showing how the same historical material continues to organize neighboring vocabulary. The named historical forms include Old English fȳst and Proto-Germanic *fūstiz, keeping the history tied to concrete forms rather than a loose resemblance. Its semantic neighborhood includes handful, grasp, and clutch, locating the modern specialization without adding a new origin story.