Translation guide
The English word "deadly" has several distinct meanings. This guide helps learners choose the right Japanese expression depending on whether they mean "causing death," "extremely effective or accurate," "very boring or dull," or "like death in appearance."
Describing something that can kill, such as poison, weapons, diseases, or situations.
He made a deadly mistake.
Literally "life-taking." Often used for mistakes, habits, or decisions that prove fatal or ruinous.
その油断が命取りになった。
That carelessness proved deadly.
Technical/medical term meaning "lethal" or "deadly." Used for diseases, doses, etc.
これは致死性のウイルスです。
This is a deadly virus.
Describing a person or thing that is highly skilled, precise, or devastatingly effective, often in sports, arguments, or performance.
Can also be used figuratively to mean "devastatingly effective," especially for attacks, shots, or arguments.
彼のシュートは致命的だ。
His shot is deadly.
Literally "hundred shots, hundred hits." Means unerringly accurate, deadly accurate.
彼は百発百中のシューターだ。
He is a deadly shooter.
Means "tremendous" or "immense." Can describe deadly effectiveness in some contexts.
彼の批判は絶大な効果を発揮した。
His criticism had a deadly effect.
Describing something that is so uninteresting it feels almost unbearable.
Literally "boring to the point of dying." A very common and natural way to say "deadly boring."
その会議は死ぬほど退屈だった。
The meeting was deadly boring.
A more formal and emphatic way to say "extremely boring."
その講義は退屈極まりなかった。
The lecture was deadly dull.
Describing a pale, ghostly, or deathly appearance, silence, or stillness.
Literally "like a dead person." Used for pale faces or deathly appearance.
彼女は死人のように青白かった。
She had a deadly pale face.
Means "death-like." Used for silence, stillness, or atmosphere.
死のような静けさが広がった。
A deadly silence spread.
Do not use 致命的に退屈 (chimeiteki ni taikutsu). While grammatically possible, it sounds unnatural. Use 死ぬほど退屈 (shinu hodo taikutsu) instead.
致命的 (chimeiteki) is more common and can be used for both literal and figurative deadly things. 命取り (inochitori) often implies a fatal flaw or mistake that leads to ruin, and is slightly more dramatic.