(n.) That which annoys or gives trouble and vexation\; that which is offensive or noxious.

aggravation annoyance ass bad news bedevilment besetment bore bother botheration bothersomeness burden buttonholer crashing bore devilment difficulty dogging downer drag drip dryasdust dusty exasperation flat tire frightful bore harassment harrying hassle headache hounding humdrum inconvenience irritant irritation molestation nag ordeal persecution pest pester pesterer pill plague problem proser tease tormenter tormentor trial trouble twaddler vexation vexatiousness wet blanket worriment worry