The Hebrew noun keli is a broad term meaning vessel, article, implement, instrument, or weapon. Occurring about 325 times in the OT, it is one of the most versatile nouns in biblical Hebrew. It covers everything from temple vessels to musical instruments to weapons of war — anything formed and used for a purpose.
Keli becomes theologically rich when applied to people. Isaiah 54:16 describes God as the One who creates weapons (keli) — both the destroyer and the deliverer. Paul picks up this vessel imagery: believers are 'vessels' of mercy prepared for glory (Romans 9:23), and Paul himself is God's 'chosen instrument' (Acts 9:15). The temple vessels, captured by Babylon and restored under Ezra, symbolize God's holiness and His people's restoration. A keli is only as useful as what it holds and whom it serves.