buster
n. countable B2 Upper Intermediate US //ˈbəstɝ// UK //bˈʌstɐ// buster
n. a person or thing that causes something to end or fail. You use it to describe the final blow in a fight or the reason a plan stopped.
n. a decisive factor or agent that brings about the end, defeat, or destruction of something. Informal register; often used in compound nouns.
The sudden rain was the buster of our picnic.
The unexpected budget cut was the buster of the company's expansion plans.
In the context of the Cold War, the economic stagnation of the 1970s served as the ultimate buster of Soviet ideological confidence.