A floating-for-floating swap whose first floating rate leg is derived from the returns on a basket of underlying assets, such as equities, commodities, bonds, or even swaps. The other floating leg is so often a reference interest rate (such a LIBOR) with a discount or premium spread.
The floating rate leg is exchanged for another floating rate leg on a regular basis over the lifespan of the swap:
Floating rate 1 <==> floating rate 2 ± spread
