Plain English Meaning

It is the tiny spout inside the carburetor where fuel comes out and gets mixed into the air being sucked into the engine.

Full Definition

In a float-type carburetor, the discharge nozzle is the small outlet, located in the venturi, through which fuel is drawn from the float chamber and sprayed into the airstream entering the engine. The pressure drop created by air accelerating through the venturi pulls fuel up through the nozzle, where it atomizes and mixes with the incoming air to form the combustible fuel-air charge.

Context Anchor

Seen in carburetor diagrams and explanations of how fuel leaves the float chamber and enters the airflow.

Derivation

‘Discharge’ comes from the Old French ‘descharger’, meaning to unload or release. ‘Nozzle’ is a small ‘nose’ — a projecting spout. Together: the small spout that releases the fuel.