Definitions
01one who kills
A2 · Elementary Countable noun
n. a person, animal, or thing that causes death.
n. a person, animal, or agent that causes the death of another living being.
“The police are still searching for the killer after the attack.”
“The documentary explores how the invasive species became a silent killer of the local bird population within just a few years.”
Antonyms
02something very difficult
B2 · Upper Intermediate Countable noun Informal
n. something that is extremely hard to do or causes a lot of stress.
n. a task, situation, or experience that is exceptionally taxing or difficult to endure.
“That three-hour exam was a real killer.”
“The final climb of the race is a absolute killer, forcing even the most seasoned cyclists to push their physical limits.”
03killer whale
B1 · Intermediate Countable noun Science
n. another name for an orca.
n. a common shorthand for the orca (Orcinus orca).
“We saw a pod of killer whales swimming near the boat.”
“Marine biologists observed the killer whales using sophisticated hunting techniques to isolate their prey from the rest of the pod.”
Synonyms
04excellent or impressive
B2 · Upper Intermediate Slang
adj. very impressive, effective, or cool.
adj. strikingly effective, impressive, or fashionable. Often used in marketing or casual praise.
“She gave a killer presentation that convinced the whole board.”
“The startup's new app features a killer interface that sets it apart from every other competitor in the crowded fintech market.”
Synonyms
05causing death
B2 · Upper Intermediate
adj. deadly or very dangerous.
adj. having the capacity or tendency to cause death or total destruction.
“The city was hit by a killer heatwave last summer.”
“The researchers identified a killer strain of the virus that appeared resistant to conventional antibiotic treatments.”
Antonyms
Collocations
Common phrases and expressions where native English speakers use the word “killer” in context.
Real-World Examples
“Heat is the leading weather-related killer in the United States.” “Government sources confirmed on Monday night that officials were still examining whether they could block the release of Harper’s killers.” Etymology
From Middle English killer, kyller. By surface analysis, kill + -er.
Etymology adapted from Wiktionary, available under CC BY-SA 4.0.
Word family
VERB
NOUN
Related words
Idioms
Domain
- Exam level
- CambridgeCambridgeCambridge English QualificationsThe exam suite from Cambridge University Press & Assessment, from A1 Movers up to C2 Proficiency. The benchmark names double as CEFR labels.B2 FirstIELTSIELTSInternational English Language Testing SystemThe 0–9 band test co-owned by the British Council, IDP, and Cambridge. Used for university entry, work, and migration.5.5–6.5TOEFL iBTTOEFL iBTTest of English as a Foreign Language, Internet-Based TestETS's academic English test, the standard route for US university admissions. Scored 0–120, with a 1–6 scale since 2026.1–6 scale: 4.0–4.572–94TOEICTOEICTest of English for International CommunicationETS's workplace English test, big in Japan and Korea. Listening & Reading scores 10–990 and tops out at C1.785–944
- Frequency
- Common
- Level
- B2 · Upper Intermediate
- Updated
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englishreference.com/q/killer
「カタカナ語」 data: JMdict (EDRDG), CC BY-SA 4.0