A measure of the money supply used by the various central banks that includes only currency in circulation and very near money instruments. In the Federal Reserve System, narrow money includes all physical currency and deposits in checking accounts as well as Negotiable Orders Withdrawal accounts. It does not include savings accounts, certificates of deposit, or money market accounts. This is called narrow money because it applies the most restrictive definition of money. It is also called the money base. See also: M1, M0.