Step 1: Define clearly.
Unlike irredeemable debentures (not permitted in many jurisdictions), a \emph{redeemable} debenture carries a commitment to return principal on or before a stated maturity date.
Step 2: Redemption terms.
Repayment can be in lump sum, by instalments/draw of lots, by purchase in open market, or via conversion—at par or premium as agreed.
Final Answer:
\[
\boxed{\text{Debenture repayable at/within a specified time as per issue terms}}
\]
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