Minister is the formal title for ordained clergy in most of the Reformed family of churches, and the word itself, meaning servant, carries a deliberate theological point.
Servant of word and sacrament
Given in full as minister of word and sacrament, the title is standard in the Reformed, Presbyterian, Methodist and Congregational churches, and it names the same essential work as the pastor: preaching, the administration of the sacraments, and the pastoral care and teaching of a congregation. The choice of the word servant over any title of priesthood is intentional, expressing the Reformed understanding that the office is a service within the church rather than a sacred caste set above it.
Ordination and government
A minister enters the office through a course of training and formal ordination by the wider church, most characteristically by a presbytery or equivalent body rather than by a single bishop, which reflects the collegial and representative government of these churches. In Presbyterian polity the minister is a teaching elder who shares the government of the church with the ruling elders elected by the congregation, so the office is set within a structure of shared authority rather than a hierarchy of orders. The ordination of women as ministers is now general in much of this family of churches, though it remains contested in some.