1kill·er 
/ˈkɪlɚ/ noun
plural kill·ers /ˈkɪlɚ/ noun [count] 1 : a person or thing that kills someone or something
▪ The police finally captured the killer. [=murderer] ▪ Heart disease is the leading killer of both men and women. ▪ The chemical is used as a weed killer. 2 informal : something that is very difficult
▪ That exam was a (real) killer. = That sure was a killer of an exam.
▪ The police finally captured the killer. [=murderer] ▪ Heart disease is the leading killer of both men and women. ▪ The chemical is used as a weed killer.
▪ That exam was a (real) killer. = That sure was a killer of an exam.
