The word vexed means of something that causes trouble or bother someone. In the text the word vexed is used like this, "And this I did for seven long nights—every night just at midnight—but I found the eye always closed; and so it was impossible to do the work; for it was not the old man who vexed me, but his Evil Eye. I figured out my definition because the the narrator says that he did not like the old man's eye and that it haunted him.
