Aggravation is the feeling of being annoyed or frustrated, especially when something keeps bothering you or making a situation worse. When your little brother keeps poking you while you're trying to read, that's an aggravation. When you're already running late and then can't find your homework, the lost assignment becomes another aggravation piled on top of the first problem.

You can feel that weight when aggravations pile up. One rainy day might be fine, but a whole week of rain that cancels recess becomes a real aggravation. A single mosquito bite itches, but ten mosquito bites create serious aggravation.

You'll also hear the verb form: something aggravates you when it makes you annoyed, or it aggravates a problem when it makes the problem worse. A cough might aggravate a sore throat. Complaining might aggravate an already tense situation.

People sometimes confuse aggravate with irritate, and while they're similar, aggravate suggests making something that's already bad even worse. An irritation might be the first annoyance, but aggravation is what happens when that irritation keeps growing or won't go away.