Tsaba means army, host, military service, or warfare. It appears about 485 times. It describes Israel's armies, angelic hosts ('LORD of hosts'), and the heavenly bodies ('host of heaven').
'LORD of hosts' (YHWH Tsaba'oth) emphasizes God's sovereignty over all armies — earthly and heavenly. God commands both the armies of Israel and the angelic host. This title became dominant in the prophetic books, declaring God's supreme military power.