3N-COUNT 恼人的情景;惹人烦的局面 If you refer to a situation as a nightmare, you are saying in a very emphatic way that it is irritating because it causes you a lot of trouble. 恼人的情景;惹人烦的局面 [emphasis]
Taking my son Peter to a restaurant was a nightmare.
带我儿子彼得外出吃饭简直糟糕透了。
In practice a graduate tax is an administrative nightmare.