Plain English Meaning
A small metal lever sticking out of the carburetor. The cockpit throttle cable pulls or pushes this lever, which is how cockpit controls actually move parts inside the carburetor.
Full Definition
The external lever attached to the throttle or mixture shaft of an aircraft carburetor that the control cable connects to. When the pilot moves the throttle or mixture control in the cockpit, the cable rotates this arm, which in turn opens or closes the throttle butterfly valve or adjusts the fuel mixture inside the carburetor.
Context Anchor
You may hear this term during engine- explanations, discussions, or a of the engine with the open.