Diakonia (Greek) is a noun used 32 times in the New Testament and variously translated as “ministry,” “service,” “relief,” or “support.” It is used in Luke 10:40 of Martha’s meal preparations for the Lord, while Mary sat at His feet and listened to Him. It is used in Acts 6:1 regarding the serving of food and in Acts 6:4 referring to the “ministry of the Word.” In Acts 11:29 diakonia refers to famine relief in the form of a monetary contribution. In Acts 20:24 and 21:19, Paul uses the word to refer to his ministry among the Gentiles. In Romans 12:6–7 it is referred to as a spiritual gift—the gift of serving.
As with the English word service, diakonia can have a variety of meanings and nuances depending on the context. You can go to a worship “service,” you can go to a “service” station, and you can order room “service.” On one hand, the three seem to have nothing in common, but, on the other hand, they all have to do with the provision of one kind of service or another. It would be wrong to try to build a composite definition of service based on all three contexts, and then plug that definition back into each context. For instance, a worship service is NOT a place where you can go to worship God, have your oil changed, and have a meal delivered to you.
The best way to get a feel for the meaning of a word in the Bible is to read every passage where the word is used. The passages chosen should be based on their use of the original Greek or Hebrew word, not the English translation. With modern technology and free online Bible study tools, it is not difficult to do a word study, even if you have not studied Hebrew or Greek. There are also word study books (not to mention internet articles) that will do the work for you, but nothing will give you a better understanding of a word than reading all the passages for yourself.
Another noun that corresponds to diakonia is diakonos, which most basically means “servant” (“one who serves”). Diakonos eventually became a technical term, deacon, which denotes a church office. The qualifications for a deacon are found in 1 Timothy 3:8–13. In the more technical definition, a deacon is one who serves the physical needs of the church, as opposed to the elders/pastors who tend to the spiritual needs of the church. (Acts 6:1–7 is the key passage on this point.) However, both the physical and the spiritual ministrations can be described by the word diakonia. Careful attention to the context will reveal what kind of service is being rendered.