The Words for Slave, Slavery

The Greek words for slave, slavery are also the words translated serving, serve, servant, or bond-servant.

Colossians 3:23-24 is a good passage to see the use of this word.  There are many others and we may add to this article as time progresses. 

JESUS AS LORD AND JUDGE (3:23–24). Paul reminds slaves that they ultimately are serving not their earthly masters but “the Lord Christ”—or, one could say, “the true Master (kyrios), Christ,” who is Lord of all. Most scholars argue that the Greek verb should be read as a command: “Serve the Lord Christ” (douleuete, “serve,” can be either indicative or imperative). In the context of verse 24, they are likely correct, for Paul is challenging the slaves to consciously and actively make Christ the object of their service. In a temporary human sense, of course, they serve their human owners, but the lordship of Christ is paramount. Everything slaves do in the household they do as Christians, and thus for the glory of God and Christ.  [Osborne, G. R. (2016). Colossians & Philemon: Verse by Verse (p. 125). Bellingham, WA: Lexham Press.]

douleuete  δουλεύω, I serve as a slave, I am a slave. – Most often translated as serving or serve. However service in the first century was nearly always done by those who were considered some kind of slave and not free persons.

doulois  δοῦλος, (a) (as adj.) enslaved, subject; (b) (as noun) a (male) slave.  -  Most often translated as bondservant or bond-slave.  These slaves were often, of their own volition made slaves for life at the time that they had completed their indentured service. 

δουλόω, I enslave.