killer
[noun]
Synonyms: assassin, butcher, cut-throat, executioner, exterminator, gunman, hit man (slang), murderer, slayer

[TahlilGaran] English Synonym Dictionary ▲

I. kill‧er¹ /ˈkɪlə $ -ər/ noun [countable]
[Word Family: noun: kill, overkill, killer, killing; verb: kill; adjective: killer]

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.

[TahlilGaran] Dictionary of Contemporary English ▲

II. killer² adjective [only before noun]
[Word Family: noun: kill, overkill, killer, killing; verb: kill; adjective: killer]

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.

[TahlilGaran] Dictionary of Contemporary English ▲

killer
noun
ADJ. big, major Overdoses were the single biggest killer among the city's young.
real I don't care what they ask me if it helps them find the real killer.
alleged | convicted | notorious | brutal, vicious | crazed, psychopathic | mass, serial | contract, hired | child, wife, etc. a convicted child killer
giant (figurative) Salford Juniors proved to be the giant killers in last week's semi-finals (= by beating a much better team).
VERB + KILLER hunt, track down | catch, find
KILLER + VERB strike The killer has struck again.
KILLER + NOUN bug, disease, virus Heart attacks have become Britain's No. 1 killer disease.
instinct (figurative) He plays well but still lacks the killer instinct.
blow (figurative) Owen delivered the killer blow soon after half-time.

[TahlilGaran] Collocations Dictionary ▲