flint fire; flash
Literally the spark from striking flint; often used metaphorically for something extremely brief or instantaneous. Common in the idiom 石火の光 (a flash of light) or in expressions like 石火の如く (like a flash).
It was a momentary event, like a flash of light from flint.
His movement was as quick as a flash.
lightning speed; in a flash; instantaneous
Compound of 石 (stone) and 火 (fire), referring to the spark produced by striking flint. The exact historical derivation is uncertain, but the word has been used in classical Japanese to denote something fleeting.