What is Equity-linked Note?

Legal Definition
Equity-linked note (ELN) is a debt instrument, usually a bond, that differs from a standard fixed-income security in that the final payout is based on the return of the underlying equity, which can be a single stock, basket of stocks, or an equity index. Equity-linked notes are a type of structured products.

Most equity-linked notes are not actively traded on the secondary market and are designed to be kept to maturity. However, the issuer or arranger of the notes may offer to buy back the notes. Unlike the maturity payout, the buy-back price before maturity may be below the amount invested in first place.
-- Wikipedia
Legal Definition
A security whose gain is based on another instrument, a sector index, or broader market index. This basis is not on any yield by interest rate. Often, such a linked security protects the principal by having a set minimum on redemption value.