Fixed-income securities are financial instruments that pay a fixed amount of interest or return to the investor over a specific period. Understanding the defining elements of fixed-income securities is essential for investors to make informed investment decisions. The following are the key elements that define fixed-income securities:

1. Coupon Rate: The coupon rate is the fixed interest rate that the issuer pays to the investor at regular intervals until the maturity of the security. It is expressed as a percentage of the face value of the security.

2. Face Value: Face value is the nominal value of the security that the issuer promises to pay the investor at maturity. It is also known as par value or principal value.

3. Maturity Date: The maturity date is the date when the issuer pays the face value of the security to the investor. It is the end of the term of the security.

4. Yield: Yield is the total return that an investor earns on a fixed-income security, including the coupon payments and any capital gains or losses. It is expressed as a percentage of the current market price of the security.

5. Credit Rating: Credit rating is an assessment of the issuer's ability to pay back the principal and interest on the security. It is assigned by credit rating agencies based on the issuer's financial strength and creditworthiness.

6. Liquidity: Liquidity refers to the ease with which an investor can buy or sell a security in the market. Highly liquid securities are easy to trade, while illiquid securities may be difficult to sell.

7. Callability: Callability is the issuer's right to redeem the security before its maturity date. Callable securities usually offer a higher coupon rate to compensate investors for the risk of early redemption.

By understanding these defining elements, investors can evaluate the risk and return of fixed-income securities and make informed investment decisions.