Fumble
late Middle English: from Low German fommeln or Dutch fommelen .
wiktionary
Late Middle English, from Low German fommeln or Dutch fommelen. [1]
Or, perhaps from a Scandinavian/North Germanic source; compare Old Norse fálma, Swedish fumla, Danish fumle, German fummeln.
The ultimate origin for either could perhaps be imitative of fumbling. [2] Or, from Proto-Indo-European *pal-(“to shake, swing”), see also Latin palpo(“I pat, touch softly”), and possibly Proto-West Germanic *fōlijan(“to feel”). [3]
Blend of fool + crumble.
etymonline
fumble (v.)
mid-15c., "handle clumsily," possibly from Old Norse falma "to fumble, grope." Similar words in Scandinavian and North Sea Germanic (Swedish fumla; Dutch fommelen) suggest onomatopoeia from a sound felt to indicate clumsiness (compare bumble, stumble, and obsolete English famble, fimble of roughly the same meaning). Intransitive sense "do or seek awkwardly" is from 1530s. Sense in football is from 1889. Related: Fumbled; fumbling.
fumble (n.)
1640s, from fumble (v.).
