Flummox

Word meaning -

verb: confuse

Usage examples -

I'm flummoxed by ...

Etymological note - (from Merriam-Webster)

No one is completely sure where the word "flummox" comes from, but we do know that its first known use is found in Charles Dickens' 1837 novel The Pickwick Papers and that it had become quite common in both British and American English by the end of the 19th century. One theory expressed by some etymologists is that it was influenced by "flummock," a word of English dialectical origin used to refer to a clumsy person. This "flummock" may also be the source of the word "lummox," which also means "a clumsy person."