to plunder: to seize and carry off goods, wealth, or captives by force, especially from a defeated enemy in war.
This is the language of war and raid. When an army overruns a city or a people, this verb describes what the victors do to the losers' possessions: they seize the silver and gold, the livestock, and the goods, and carry them off. The wealth taken this way is the "spoil", and the verb travels constantly alongside its own noun (שָׁלָל, "spoil, plunder").
The Bible uses the word with a striking evenhandedness. The same act is plunder whether Israel's enemies do it to Israel or Israel's God turns it back on them. The prophets announce that Babylon, which stripped so many nations, will itself be stripped, and that those who plundered God's people will in turn become plunder. The word carries no built-in verdict of right or wrong; the surrounding story supplies that.
It also has a passive side. A person or a people can be the ones despoiled, left stripped and defenseless. In one pointed line, the man who turns away from evil finds himself treated as easy prey by a corrupt society.