vexation

A vexation is an annoying or frustrating problem that keeps bugging you.

When we say someone has a vexation, we usually mean they're dealing with a big headache – not necessarily one of those physical headaches, but more like a mental one. It could be anything from a noisy neighbor who won't stop making noise to a difficult project at work that's taking up all your time and energy. Sometimes people use the word "vexation" in writing or conversation when they're describing how someone is being really bothered by something – it's an old-fashioned way of saying they're annoyed or irritated, but it sounds more formal and interesting. For example: "The driver was at his wits' end due to the vexation caused by a burst tire on the highway."