2. (noun)cause of death, killer the causal agent resulting in death "heart disease is the biggest killer in the United States"
3. (noun)killer a difficulty that is hard to deal with
"that exam was a real killer"
4. (noun)killer whale, killer, orca, grampus, sea wolf, Orcinus orca predatory black-and-white toothed whale with large dorsal fin; common in cold seas