commons (n.)

mid-14c., "the people collectively," especially "the common people as distinguished from the rulers and nobility and the clergy; the freemen of England as represented in Parliament" (late 14c.), from common (n.). Meaning "the lower house of Parliament, consisting of commoners chosen by the people as their representatives" is from early 15c. House of Commons is from 1620s. Meaning "provisions for a community or company" is from mid-14c.