Bln meaning : (modern British & Australian, short scale) a thousand million (logic: 1,000 × 1,000^2): 1 followed by nine zeros, 109; a milliard (British & Australian, long scale) A million million (logic: 1,000,000^2): a 1 followed by twelve zeros; 1012 An unspecified very large number. Initialism of Brown lunation number.