ETYM Old Eng. diakne, deakne, deken, AS. diacon, deacon, Latin diaconus, from Greek diakonos a servant or minister, a minister of the church; of uncertain origin.
1. A Protestant layman who assists the minister; SYN. Protestant deacon.
2. A cleric ranking just below a priest in Roman Catholic churches; SYN. Catholic deacon.

In the Roman Catholic and Anglican churches, an ordained minister who ranks immediately below a priest. In the Protestant churches, a deacon is in training to become a minister or is a lay assistant.