vexatious

adjective

1. 1

   Causing vexation or annoyance; teasing; troublesome.

2. 2

   Full of trouble or disquiet

3. 3

   (of an action) Commenced for the purpose of giving trouble, without due cause.

   “a vexatious lawsuit”

4. 4

   (of a party or entity) In the habit of starting vexatious litigation and therefore liable to have restraints placed on one's ability to access the courts.

   “a vexatious litigant”