parliamentarian

Short definition from Wiktionary

Noun

1. 1
   A member of a parliament, congress or an elected national legislative body of another name.
2. 2
   A person well-versed in parliamentary procedure.
3. 3
   An officer in most legislative bodies charged with being well-versed in the parliamentary rules of that legislative house, and whose rulings are taken as authoritative, to be appealed only to the whole of the house itself under special rules.
4. 4
   Alternative letter-case form of parliamentarian, particularly
5. 5
   Alternative letter-case form of parliamentarian, particularly: A supporter of the English Parliament during the English Civil War.

Adjective

1. 1
   Of or relating to a parliament; favouring the establishment of a parliament.
2. 2
   Of or relating to the Parliamentarians (supporters of the parliament during the English Civil War (1642–1651)).