flash point

lowest temperature at which a substance produces vapors that ignite immediately when subjected to a flame (Chemistry); critical point that causes change; situation that will likely become violent

The flash point of a flammable liquid is the lowest temperature at which it can form an ignitable mixture in air. At this temperature the vapor may cease to burn when the source of ignition is removed. A slightly higher temperature, the fire point, is defined as the temperature at which the vapor continues to burn after being ignited. Neither of these parameters are related to the temperatures of the ignition source or of the burning liquid, which are much higher. The flash point is often used as one descriptive characteristic of liquid fuel, but it is also used to describe liquids that are not used intentionally as fuels.
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Noun
1. point at which something is ready to blow up
(synonym) flashpoint
(hypernym) criticality
2. the lowest temperature at which the vapor of a combustible liquid can be ignited in air
(synonym) flashpoint
(hypernym) temperature

The lowest temperature at which evaporation of a substance produces sufficient vapor to form an ignitable mixture with air.

Compare with auto-ignition temperature .The temperature when vapor pressure of a substance becomes high enough to allow the air/vapor layer over the substance to be ignited. Ether and acetone have flash points below room temperature, which makes them very dangerous.