a leader: the one placed out front and at the head of others, with the authority to direct them
This word pictures the person who stands in front. Its root has the sense of being conspicuous, set before others, and the leader it names is the one others look to and follow. The same word covers a wide span of authority, from the king set over a whole nation down to the officer put in charge of a single department, because what they all share is that one quality: they are the one in front.
Most often the leader is someone God himself appoints over his people. When Samuel anoints Saul, and later David, the word marks them as God's chosen ruler before they ever hold a crown, which is why it can carry the weight of a divine commission rather than just a job title. Israel's writers favored it for exactly this reason: it says the throne is granted, not seized.
In the records of the temple and the kingdom the same word drops to ground level and simply means the official set over something, the chief of the treasuries, of the army, of a clan, of the house of God. And in poetry and prophecy it widens again to mean a prince or noble of any nation, including rulers far from Israel. The English Bible spreads it across ruler, leader, prince, captain, chief, and governor, but in the Hebrew it is one word doing one thing in many settings.