stump
v.v. to be completely confused or unable to answer a question. You use this when a problem is too difficult for you to solve.
v. to present a problem or question that proves impossible to solve or answer; to baffle or nonplus. Often used in the passive voice when describing a person's state of confusion.
That difficult math question really stumped me.
Even the most experienced mechanics were stumped by the strange noise coming from the engine.
The investigators were completely stumped by the lack of physical evidence at the scene, leading them to reconsider their initial theory of the crime.
From Middle English stumpe, stompe (“stump”), from or akin to Middle Low German stump (“stump”) or Middle Dutch stomp, from Old Saxon or Old Dutch stump, from Proto-West Germanic stump, from Proto-Germanic *stumpaz (“stump, blunt, part cut off”). Cognate with Middle Dutch stomp (“stump”), Old High German stumph (“stump”) (German Stumpf), Old Norse stumpr (“stump”). More at stop.
The verb is transitive and takes a direct object. In political contexts, it can also mean to travel around making campaign speeches.