flashing point

GNU Webster's 1913

1. n. (Chem.) that degree of temperature at which a volatile oil gives off vapor in sufficient quantity to burn, or flash, on the approach of a flame, used as a test of the comparative safety of oils, esp. kerosene; a flashing point of 100° F. is regarded as a fairly safe standard. The burning point of the oil is usually from ten to thirty degree above the flashing point of its vapor. Usually called flash point.