killer

kill|er¹ [ˈkılə US -ər] n

1.) a person, animal, or thing that kills

▪ Heart disease is America's number one killer.

▪ the hunt for her killers

▪ weed killer

→serial killer at ↑serial² (1)

2.) informal something or someone that is very difficult, tiring, or boring

▪ The new project is a killer.

3.) informal something that is very exciting or impressive

▪ I'm not saying the film is a killer, but it's cool.

killer ²

killer² adj [only before noun]

1.) very harmful or dangerous

▪ a killer hurricane

▪ a swarm of killer bees

2.) informal very attractive, good, impressive etc

▪ a book called 'How to Build a Killer Website'

3.) killer instinct

a very strong desire to succeed in a situation or activity etc that is very competitive

▪ Young players these days lack the killer instinct.