צוּם

From LSJ

ἔξαψις σφοδρὰ μετὰ πολλῆς βίας πίπτουσα ἐπὶ γῆς → a violent flare-up falling on the ground with great force, thunder and lightning

Source

English (Strong)

a primitive root; to cover over (the mouth), i.e. to fast: X at all, fast.