RhymeZone: killer definitions

Definitions of killer:

noun: a difficulty that is hard to deal with
Example: "That exam was a real killer"
noun: someone who causes the death of a person or animal
noun: predatory black-and-white toothed whale with large dorsal fin; common in cold seas
noun: the causal agent resulting in death
Example: "Heart disease is the biggest killer in the United States"
name: A surname (very rare: popularity rank in the U.S.: #62862)