ου, ὁ, ἡ (s. διακονέω, διακονία) gener. one who is busy with someth. in a manner that is of assistance to someone1. one who serves as an intermediary in a transaction, agent, intermediary, courier. Of a deity’s intermediaries; of officials understood collectively as a political system agent : of apostles and other prominent Christians charged with its transmission; of Christ as God’s agent; of Tychicus as faithful courier
2. one who gets someth. done, at the behest of a superior, assistant to someone. Of table attendants. Of a king’s retinue Mt 22:13.—Of Jesus’ adherents gener.: those in the service of Jesus. Satirically, ἁμαρτίας δ. agent for sin Gal 2:17. One who serves as assistant in a cultic context attendant, assistant, aide
(BDAG -- dictionnaire standard grecque)