Meaning

noun a building occupied by a state legislature

noun the government building in Washington where the United States Senate and the House of Representatives meet

originFrom Middle English Capitolie, via Anglo-Norman capitolie, Old French capitoile, from Latin Capitōlium (“Capitoline Hill, its temples; any similar citadel”), from the oblique stem of caput (“head”) + -ō (noun-forming suffix) or -ōlus (“-ole”, diminutive suffix) + -ium (toponym-forming suffix). Compare Latin capitō and capitulum. As a French magistrate, via French capitoul, from Capitole, the town…

Etymology from Wiktionary, CC BY-SA 3.0