What does "deaconess" mean?

Deaconess: A female deacon; as: (a) (Primitive Ch.) One of an order of women whose duties resembled those of deacons. (b) (Ch. of Eng. and Prot. Epis. Ch.) A woman set apart for church work by a bishop. (c) A woman chosen as a helper in church work, as among the Congregationalists.