A nozzle adapter is a fitting that connects two pipes of different sizes or types. The "female" end of the adapter has an inward-facing threaded connection, while the "male" end has an outward-facing threaded connection. By connecting these two different types of fittings, the adapter allows for a connection between two components that would otherwise be incompatible. Nozzle adapters are commonly used in a variety of applications, where different pipes need to be connected.