Question

look at this thesaurus entry:
calamity
part of speech: noun
definition: a catastrophe
synonyms: accident, disaster, tragedy, trouble
which is a calamity?
a bad grade
a hurricane

Explanation:

A calamity is defined as a catastrophe, with synonyms like disaster. A hurricane is a natural disaster (catastrophe), while a bad grade is a minor setback, not a catastrophe. So a hurricane fits the definition of calamity.

Answer:

a hurricane