Definitions
1.nounOne who advocates reform (of an institution).
2.nounSpecifically, one who advocates reform of society and the gradual accumulation of small changes, as opposed to revolutionary action.
3.noun(17th C.) An advocate of reform in the Church of England; a Reformer.
4.noun(18th century) An advocate or supporter of political reform in the United Kingdom. (Common from ca 1790 to 1830.)
5.nounA member of a reformed religious denomination.