parliamentarian

noun3

1. •
   (Commonwealth) A member of a parliament, congress or an elected national legislative body of another name.
2. •
   A person well-versed in parliamentary procedure.
3. •
   (US) 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.

adjective2

1. •
   Of or relating to a parliament; favouring the establishment of a parliament.

   • Our participation in the parliament does not indicate a support, but rather an undermining of the parliamentarian system. — 1946
2. •
   (historical) Of or relating to the Parliamentarians (supporters of the parliament during the English Civil War (1642–1651)).

   • But while he continued there, he shew’d himself a Dunce, a Tale-bearer to the Parliamentarian Visitors that then acted in the University, and a factious person. — 1692

noun2

1. •
   (historical) A supporter of the English Parliament during the English Civil War.
2. •
   Alternative letter-case form of parliamentarian.