1837, cant word, origin uncertain, probably from some forgotten British dialect. Candidates cluster in Herefordshire, Gloucestershire, southern Cheshire and also in Sheffield. "The formation seems to be onomatopœic, expressive of the notion of throwing down roughly and untidily." Never let it be said that the OED editors lacked imagination. Related: Flummoxed.
A failure; disaster; fuck-up: The solemn commemoration was a total flummox (1851+)
To spoil; upset; confound: Fu-Manchu tries to abduct a missionary who has flummoxed his plans in China (1837+)
[fr British dialect, ''maul, bewilder'']