Vexatious (adjective)

1. Causing annoyance, frustration, or worry; harassing.
2. Annoying, troublesome, or causing irritation.

Origin:

Late middle english: from old french vexatif, -ive or latin vexatius, from vexare "to trouble".

Examples:

1. The vexatious litigation has caused a lot of stress for the company.
2. The vexatious employee was always causing problems.
3. He found the whole situation vexatious and wished it would just go away.
4. Vexatious behavior is not tolerated in the workplace.
5. The vexatious rule was changed after it caused widespread complaints.