Plain English Meaning
It is the change of liquid fuel into a gas so it can mix with air and burn inside the engine. Liquid fuel will not burn well on its own; it has to turn into vapor first.
Full Definition
The process by which liquid fuel changes into a vapor so it can mix with air and burn properly in the engine's cylinders. In a reciprocating aircraft engine, fuel must vaporize before combustion can occur, and this change of state is influenced by temperature, pressure, and the design of the induction system.
Context Anchor
Seen in induction system and carburetor discussions, especially when explaining fuel-air mixture, engine smoothness, and carburetor icing .