Plain English Meaning
A chemical added to fuel in tiny amounts to stop water in the fuel from freezing and clogging the fuel system when it's cold.
Full Definition
A fuel system icing inhibitor additive blended into aviation gasoline in small, controlled concentrations to prevent water suspended in the fuel from freezing and forming ice crystals that could block fuel filters or fuel lines at low temperatures.
Context Anchor
Seen in fuel-system discussions about preventing water-related fuel icing, especially in procedures for cold-weather or high-altitude operations.