A swap which is based on two floating rates of the same currency but with different tenors (e.g., a 6-month LIBOR (or any other floating rate) versus 5 year constant maturity swap rate) or on two floating rates denominated in two different currencies (6-month US dollar LIBOR versus 6-month Euribor) where the notional amounts are exchanged both at the start of the swap and at maturity date.
The floating-floating swap is also referred to as a basis swap or a basis rate swap.
