The term fixed maturity is applicable to any form of financial instrument under which the loan is due to be repaid on a fixed date. This includes fixed interest and variable rate loans or debt instruments, whatever they are called, and also other forms of security such as redeemable preference shares, provided their terms of issue specify a date. It is similar in meaning to 'redemption date'. However some such instruments may have no fixed maturity date. Loans with no maturity date continue indefinitely (unless repayment is agreed between the borrower and the lenders at some point) and may be known as 'perpetual stocks'. Some instruments have a range of possible maturity dates, and such stocks can usually be repaid at any time within that range, as chosen by the borrower.
A serial maturity is when bonds are all issued at the same time but are divided into different classes with different, staggered redemption dates.
In the financial press the term maturity is sometimes used as shorthand for the securities themselves, for instance In the market today, the yields on 10 year maturities increased means that the prices of bonds due to mature in 10 years time fell, and thus the redemption yield on those bonds increased.