large-scale disaster; catastrophe
Refers to a major calamity or catastrophe, often natural or societal in scale.
The earthquake was a large-scale disaster for the whole country.
Compound of 大 (dai, 'big, large') and 災難 (sainan, 'disaster, calamity'). The exact historical derivation is uncertain, but the word follows a common pattern of intensifying a noun with 大.