KILLER

[noun] [C]Police are still hoping to find the dead woman's killer (= person who killed her).Heart disease is the number-one killer of (= cause of deaths among) American men.This chemical is found in most weed killers (= substances used to kill weeds).(informal) If something is described as a (real) killer, it is especially difficult.The test was a real killer.(US and informal ANZ) A (real) killer is also a person, story, show, etc. that is very entertaining or shows great skill.a killer storyDizzy was a killer on the trumpet.(US) The killer can also be the most exciting or interesting part of a story or event.It took her six weeks to get there, but the killer was that when she arrived she discovered that she'd gone to the wrong place.I'm afraid Lawrence lacks the killer instinct (= the desire to act for his own advantage even if it harms others).A killer whale is a small black-and-white whale (= a mammal that lives in the sea) that eats large fish and other sea animals.