The Hebrew word sera·nimʹ appears to be a Philistine loanword. (Jos 13:3) It has the same consonants as the Hebrew word for “axles” at 1 Kings 7:30. It is a title that is applied to the five lords ruling the Philistine cities of Gaza, Ashkelon, Ashdod, Ekron, and Gath, apparently because of their being in a coalition or alliance. The Philistines, according to Amos 9:7, came to the coast of Canaan from Crete, near the Aegean Sea, so it is thought by some that this is an Aegean word.

The axis lords dominated Philistia as rulers of individual city-states and as a council of coequals with regard to matters of mutual interest. Achish is called king of Gath. (1Sa 21:10; 27:2) Apparently he was not a king in the usual sense but, rather, was a prince. Consequently the title of ‘prince’ (Heb., sar) is occasionally applied to these rulers.​—1Sa 18:30; 29:2-4.

These officials are frequently found cooperating in some cause. They were called together and, in turn, consulted their priests and diviners as to what to do with the captured ark of the covenant after its presence had brought a severe plague of piles, the axis lords themselves being affected. (1Sa 5:9–6:4) They collaborated when their armies would go up against Israel. (1Sa 7:7) In the case of Samson we see them working together to overcome him. (Jg 16:5) They all gathered at the house of the god Dagon at Gaza to celebrate their capture of Samson, at which time the five axis lords then in power were killed.​—Jg 16:21-30.

However, the independent city-states under them never united to form one kingdom subject to one ruler. Instead, the five chief cities with their dependent towns functioned somewhat like a confederacy, an axis. When making decisions that affected them all, the axis lords did what was agreed upon by the majority. This is seen in the decision to reject David and his men from the Philistine army, although Achish, the axis lord of Gath, with whom David had dwelt as a refugee from King Saul, was in favor of David’s force being accepted to fight with them against Saul.​—1Sa 29:2, 6, 7, 9.

Throughout Israel’s history, especially until they were subdued by David, they were the  determined enemies of Jehovah’s people and entered many times into alliance with other nations against Israel, often having Israel under oppressive domination. David reduced their power so that they were no longer a major threat. After David’s time, the term “axis lords” is no longer found, but the term “king” is applied to their rulers.​—Jer 25:20; Zec 9:5; see PHILISTIA, PHILISTINES.