Definitions for "CUSIP number"
A nine-character number that uniquely identifies a particular security. CUSIP...
A security identification code issued in conformity with the rules of the American Bankers Association's Committee on Uniform Security Identification Procedures. Codes may be obtained from http://www.cusip.com/cusip/cusip/index.html.
An identification number assigned to each maturity of an issue intended to help facilitate the identification and clearance of securities.  In some cases, separate CUSIP numbers may be assigned to different portions of a maturity that bear different interest rates or where differences exist in the terms of the securities of such maturity that may impair the fungibility of the securities within the maturity.  For example, if a portion of a maturity has been advance refunded and the remaining portion remains outstanding, each portion will be assigned a separate CUSIP number.  See:  FUNGIBILITY.