From King Dictionary of Contemporary English killer kill‧er 1 / ˈkɪlə $ -ər / ●●○ noun [countable ] 1 KILL 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 serial 2 (1 ) 2 informal GOOD/EXCELLENT 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. Examples from the Corpus killer • The judge described him as "a cold-blooded killer". • He'd been beaten about the head. 60 police officers are now searching for his killer. • But our instinctive need to fill the vacuum inspires us to the ultimate irony: We turn 12 average citizens into killers. • Tracy's schedule is a real killer. • And the real killer is, in two weeks, they will probably give the Broncos a healthy workout. • Brilliant detective work with a little luck tossed in to catch the savvy killer. • Dr Shipman is the biggest serial killer of all time. • Even serial killers get cost-of-living raises if they happen to have a pension adjusted for inflation. • The victim's best friend, Joanne, is convinced the killer is local. • Police are searching for the killer of a 9 year old boy. • Police are still searching for the killer. • Meanwhile, a reward has been offered for information which might lead to the arrest of the killer of Arthur Brumhill. • From Pennsylvania came details of a group murder, followed by the suicide of two of the killers. killer killer 2 adjective [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’ killer heels (=women’s shoes with very high heels ) 3 → killer instinct Examples from the Corpus killer • The concert was killer. • A swarm of killer bees has attacked 70 children in a village in northern Mexico. • a killer cyclone • Killer floods and hurricanes in Asia have destroyed whole towns. • If you guys like garlic, this pickled garlic is killer stuff.