Meshissah (מְשִׁסָּה) means plunder or spoil — the goods seized from a defeated enemy. It appears about 8 times and is primarily used in prophetic literature describing what will happen to Israel or its enemies under divine judgment. Isaiah 42:22 uses it to describe Israel in exile as a people who have become plunder.
Isaiah 42:22-24 is the theological heart of meshissah: a people plundered and looted, trapped in pits, with no one to rescue them. The passage asks in verse 24: Who handed Jacob over to become loot [meshissah]? Was it not the LORD, against whom we have sinned? Judgment comes when the people God made stewards become the spoil of their enemies. The good news: God does not abandon the plundered permanently (Isaiah 42:1).