In finance, an interest rate swap is an interest rate derivative. Wikipedia

An interest rate derivative Wikipedia Disambiguation

Linear interest rate derivative involving exchange of interest rates between two parties Wikidata

A contract to exchange the benefit of one interest rate with another. Often a fixed interest rate is exchanged for a variable rate so as to allow one party to remove an exposure to a variable rate for which they pay a premium on the fixed rate in order to compensate for this 'insurance'. The two rates can also be based on different currencies. Wiktionary

Financial contract. Wiktionary (translation)