This article is about Achish I. You may be looking for his grandson or Abimelech.
Meaning: angry. This is perhaps only a general title of royalty applicable to the Philistine kings.
The name of two biblical kings:
Achish had great confidence in the valor and fidelity of David  but at the instigation of his courtiers did not permit him to go up to battle along with the Philistine hosts . David remained with Achish a year and four months.