disaster (n.) Look up disaster at Dictionary.com
1590s, from Middle French désastre (1560s), from Italian disastro "ill-starred," from dis-, here merely pejorative (see dis-) + astro "star, planet," from Latin astrum, from Greek astron "star" (from PIE root *ster- (2) "star"). The sense is astrological, of a calamity blamed on an unfavorable position of a planet.