To kill means to cause a living thing to die. A farmer might kill chickens for food, a disease might kill plants in a garden, or a harsh winter might kill trees that can't survive the cold. Throughout history, people have also killed each other in wars, conflicts, and crimes.

The word appears in many common expressions that don't involve actual death. When you kill time, you're finding ways to occupy yourself while waiting, like reading a book before your appointment. A comedian might kill with a joke that makes everyone laugh hysterically. If something is killing you, it might mean it's causing you great difficulty or pain, like when a long hike is killing your feet. Athletes sometimes say they're going to kill it in a game, meaning they'll perform extremely well.

Something that's a killer can be extremely difficult or challenging, like a killer math test. Or it might be impressively good, like a killer guitar solo. Context tells you which meaning applies.