noun

• (figuratively) A source of valuable things; a storehouse.
  "It is a perfect cabinet of faithful, valuable, and extensive information; and it ought to have a place on the shelves of the most select and compact library, and be in the possession of every private family, as a work both of valuable reference."
• (historical) A size of photograph, specifically one measuring 3⅞" by 5½".
  "Holmes took a note of it. “One other question,” said he. “Was the photograph a cabinet?”"
• (politics, often capitalized) In parliamentary and some other systems of government, the group of ministers responsible for creating government policy and for overseeing the departments comprising the executive branch.
  "Lincoln had a great deal of trouble with his Cabinet because some of them got it into their heads that they, and not the President, were the policy-makers. James K. Polk had the same difficulty with his Cabinet. Franklin Roosevelt never had any difficulty with his Cabinet for the simple reason that he himself, in my opinion, spent too much time doing the work that should have been delegated to the Cabinet."
• (politics, often capitalized) In parliamentary and some other systems of government, the group of ministers responsible for creating government policy and for overseeing the departments comprising the executive branch.
  "The executive branch of Kentucky state government is structured on a program cabinet system consisting of 14 program cabinets, each headed by a secretary, who is appointed by the Governor. The program cabinets listed below and the agencies within each cabinet are designated in the statutes."