Legal Definition
A CUSIP (CUSIP) is a unique identifier assigned to a specific security, such as a stock or bond, which is used for the purpose of uniquely identifying that security in financial transactions and record-keeping.
Plain-English Translation
Think of a CUSIP as a special tag or ID number for a specific company's stock. It’s like a unique fingerprint that helps track exactly which stock is being talked about, especially when it moves between different banks or exchanges.