From Longman Business Dictionary
irredeemableir·re·deem·a·ble /ˌɪrɪˈdiːməbəl◂/ adjectiveadjFINANCE an irredeemable bond pays interest but has no MATURITY DATE (=date at which the borrower will repay the lender)There are nine British government stocks outstanding which have no final maturity; they are irredeemable bonds.
—irredeemable noun [countableC]Bonds with no redemption date are known as irredeemables, perpetuals or consols.