Plain English Meaning

Ice that forms inside the engine's air intake because fuel turning from liquid to vapor cools the air sharply, and any moisture in that air freezes onto the metal parts. It can happen on warm, humid days, not just cold ones.

Full Definition

A form of induction system icing that occurs when fuel vaporizes in the intake airstream and absorbs heat from the surrounding air, causing the air temperature to drop below freezing and water vapor to deposit as ice on the throttle plate, venturi walls, and nearby surfaces. It can form at outside air temperatures well above freezing, typically up to about 70 °F, when humidity is high.