What is Basis Swap?

Legal Definition
A basis swap is an interest rate swap which involves the exchange of two floating rate financial instruments. A basis swap functions as a floating-floating interest rate swap under which the floating rate payments are referenced to different bases.
-- Wikipedia
Legal Definition
An INTEREST RATE SWAP involving the exchange of two floating INTEREST RATE indexes for periods ranging from one to 10 years; common reference indexes include LIBOR, EURIBOR, COMMERCIAL PAPER rates, BANKER