In the wides sense, documents giving title to property or calims on income which may lodged, e.g. as security for a bank loan. Income-yielding paper traded on the stock-exchange or in secondary markets. Usually a synonym for stocks and shares. An essential characteristic of a security is that it is saleable. The main types of secruities are: Fixed interest: Debentures, preference shares, stocks and bonds (including all governement securities and local suthority securitites); Variable interest: Ordinary shares; Other: Bills of exchange, assurance policies. Securities may be redeemable or irredeemable, quoted or unquoted.
Reference: The Penguin Dictionary of Economics, 3rd edt.