The name deacon (Greek diakonos) means minister or servant. The Greek word is used in the Septuagint Old Testament in the book of Esther (Esther 2:2; 6:3) and in the New Testament (e.g. Matthew 20:28; Romans 15:25; Ephesians 3:7; etc.). There are several other texts in the New Testament (Acts 6:1-6; Philippians 1:1; Romans 16:1-2; and 1 Timothy 3:8-13) which serve as a basis for the ministry of deacons.
In the Acts of the Apostles, Saint Luke uses the word diakonia to describe the duty or form of service assigned to the "seven men of good repute, full of the Spirit and of wisdom", called to serve at the tables of daily distribution to the widows. The institution of "The Seven" is the second defined group of disciples, "The Twelve" being the first, to be given a ministry in the Church.
In his Letter to the Philippians, Paul addresses his greeting "To all the saints in Christ Jesus who are at Philippi, with the bishops (overseers) and deacons (servants)". The use of these two terms indicate that, even at this early stage, local churches had some sort of hierarchical structure.
In Romans Paul speaks of "our sister Phoebe, a deaconess (diakonai) of the Church at Cenchreae". The service performed by such women in the early Church, which was understood to be different from the service performed by men, included assisting in the baptism of women. It was necessary to have a woman present because baptism was often performed without the benefit of clothing. Although there is some historical evidence that deaconesses were charged with their ministry in a manner resembling the ordination of deacons, there was most certainly a fundamental difference in the rites. The First Council of Nicaea (A.D. 325) made it clear that "deaconesses" did not receive sacramental ordination, which was reserved to men only.
Finally, in Chapter 3 of his First Letter to Timothy, Paul gives the qualifications for deacons (1 Timothy 3:8-13). Here we can see a distinction between the men (diakonos) and the women (diakonai) who are called to service for different purposes and with different qualifications.