1.Definition: a difficulty that is hard to deal with

"That exam was a real killer"

Category: General

2.Definition: predatory black-and-white toothed whale with large dorsal fin; common in cold seas

Related Noun(s):grampus, orca

Category: Animals

3.Definition: someone who causes the death of a person or animal

Related Noun(s):slayer

Category: People

4.Definition: the causal agent resulting in death

"Heart disease is the biggest killer in the United States"

Category: General