Wet lease
In a wet lease the lessor provides the aircraft together with crew, and usually maintenance and insurance, so the lessor keeps operational control and the lessee simply buys capacity. In practice a wet lease of a business jet is functionally a charter, and in most jurisdictions the provider must hold an AOC or Part 135 certificate to do it. The term matters because 'wet' and 'dry' decide who is legally responsible for the safety of the flight. If someone offers you a jet plus pilots without a commercial certificate and calls it a dry lease, the label is wrong and the flight may be illegal.