Definition
A constriction in a tube or passage that causes the air or fluid flowing through it to speed up and drop in pressure at the narrowest point. This pressure drop can be used to draw fuel into an airstream, drive flight instruments, or measure airflow.
Plain English
A narrow spot in a tube. When air is pushed through it, the air speeds up and its pressure falls in that narrow section.
Context Anchor
You may see this term in discussions of carburetors, fuel-air mixing, older vacuum-driven instruments, and airflow through aircraft systems.
Derivation
Named after Giovanni Battista Venturi, an Italian physicist in the late 1700s who studied how fluids behave when forced through a narrowed passage. Knowing it is a person's name helps explain why the word looks unusual and is always lowercase in technical use.
Why Pilots Care
It supplies the low pressure that draws fuel into the carburetor and generates vacuum for attitude and directional instruments in many training aircraft.
Analogy
Think of a garden hose: when you squeeze the nozzle, the water speeds up as it passes through the narrow opening. A venturi does the same thing with air.
Grounding Statement
Picture air entering a wide passage, squeezing through a narrow throat, speeding up there, and creating a small low-pressure area at that narrow point.
Intuition Check
A venturi is not a fan or pump by itself. It is a shaped passage that uses moving air to create faster flow and lower pressure.
Example Sentence 1
As air flows through the carburetor venturi, its pressure drops and fuel is drawn into the airstream.
Example Sentence 2
The venturi tube in the engine-driven vacuum pump creates suction that spins the gyros in the attitude indicator.