int.

1. something or someone that causes trouble
a source of unhappiness

e.g. washing dishes was a nuisance before we got a dish washer
a bit of a bother
he's not a friend, he's an infliction

Synonym: annoyancebotherpaininflictionpain in the neckpain in the ass

2. the psychological state of being irritated or annoyed

Synonym: irritationannoyancevexation