disaster

From Italian disastro, built from dis- (bad) and astro (star) — reflecting the old belief that misfortune arrived by way of an unfavorable alignment of the stars.

What began as a literal astrological verdict — “ill-starred” — broadened over time into any sudden catastrophe, with the stargazing entirely forgotten.

The astro- root resurfaces in astronomy and astronaut; the dis- prefix shows up again in disgrace and discord.