flummox

Of uncertain origin, probably risen out of a British dialect (OED finds candidate words in Herefordshire, Gloucestershire, southern Cheshire, and Sheffield). "The formation seems to be onomatopœic, expressive of the notion of throwing down roughly and untidily" [OED]. [1]

• IPA^(key): /ˈflʌməks/

flummox (third-person singular simple present flummoxes, present participle flummoxing, simple past and past participle flummoxed)

1. To confuse; to fluster; to flabbergast.
   • 2011 January 22, “Man Utd 5 - 0 Birmingham”, in BBC‎:

     With United's movement flummoxing the visitors, Berbatov saw his low shot saved well by Ben Foster on his first return to Old Trafford.

• See also Thesaurus:confuse