douloō

Greek had one verb for living as a slave (δουλεύω) and this one for putting somebody into that position. It answers a single question: who owns this person now? Sometimes the answer is brutally literal. When Stephen retells the story of Israel in Egypt, this is the word for four hundred years of forced labor (Acts 7:6).

Most of its New Testament uses describe a person owned by a thing rather than by a master, and the things named are ordinary ones:

• the ruling powers people lived under before Christ came (Galatians 4:3)
• the rot that has already beaten a person down (2 Peter 2:19)
• too much wine, in a life that has been handed over to it (Titus 2:3)

That is stronger than saying someone is influenced, or even addicted. It says the thing holds title to them.

Then Paul does something startling with it. Twice in Romans 6 he says that people set free from sin were promptly enslaved to what is right, and to God. He does not reach for a gentler word. Freedom in his letters is never having no owner at all; it is a change of owner. He turns the same logic on himself in 1 Corinthians 9:19: free from everyone, he made himself everyone's slave in order to win them.

One use is lighter. In 1 Corinthians 7:15 a believer deserted by an unbelieving spouse "is not bound", where the slavery verb names a tie of obligation rather than ownership itself, and readers have argued ever since about exactly what is loosed there.