killer

noun
1
a person, an animal or a thing that kills
قاتل, کشنده
see also giant-killer, killer instinct, ladykiller, serial killer
2
something that is very difficult, very exciting or shows a lot of skill
چیزی که مهارت زیادی نشان می‌دهد, چیزی که بسیار هیجان‌انگیز است, چیزی که خیلی سخت است
The exam was a real killer.
The new movie is a killer.