"of or pertaining to a parliament; in accordance with the rules and usages of legislatures," 1610s, from parliament + -ary.
Entries linking to parliamentary
parliament n.
c. 1300, parlement, "consultation; formal conference, assembly," from Old French parlement (11c.), originally "a speaking, talk," from parler "to speak" (see parley (n.)); the spelling was altered c. 1400 to conform with Medieval Latin parliamentum.
Anglo-Latin parliamentum is attested from early 13c. The specific sense of "representative assembly of England or Ireland" (with capital P-) emerged by mid-14c. from the broader meaning "a conference of the secular and/or ecclesiastical aristocracy summoned by a monarch."
-ary
adjective and noun word-forming element, in most cases from Latin -arius, -aria, -arium "connected with, pertaining to; the man engaged in," from PIE relational adjective suffix *-yo- "of or belonging to." The neuter of the adjectives in Latin also were often used as nouns (solarium "sundial," vivarium, honorarium, etc.). It appears in words borrowed from Latin in Middle English. In later borrowings from Latin to French, it became -aire and passed into Middle English as -arie, subsequently -ary.
parliamentarian n.
1640s as a designation of one of the sides in the English Civil War (a partisan or supporter of Parliament as opposed to the King); meaning "one versed in parliamentary procedure" dates from 1834. See parliamentary + -ian.