What is venturi?

venturi

Glossary “venturi” Definition:
1). Narrow area in a pipe through which a liquid or a gas is permitted to flow. 2). The constriction of the air passageway between the choke and throttle plates in a carburetor, so as air flows past this constriction, its velocity increases and a partial vacuum is produced, thereby promoting a flow of fuel from the main jet nozzle.