From ACT Wiki
The purchase and cancellation of outstanding shares or other securities, usually through a cash payment to the holder.
2. Debt securities.
The paying off or buying back of a debt security by the issuer on or before its stated maturity date.
The redemption can be made at par value or at a premium, as is the custom when exercising a call option.
3. Money market funds.
A withdrawal by an investor of their investment in the fund.