Translation guide
The English word 'sleeper' has several distinct meanings. This guide covers the most common ones for learners: a person who sleeps, a train with sleeping accommodations, an unexpected success, and a spy or agent who remains inactive for a long time.
The sleeper in the next seat is snoring.
Attach to adjectives to describe a type of sleeper. For example, 'light sleeper' is 眠りが浅い人 (ねむりがあさいひと) or more naturally expressed as 寝つきが悪い (ねつきがわるい) or ちょっとした物音で目が覚める (ちょっとしたものおとでめがさめる).
I'm a light sleeper, so I wake up at the slightest noise.
A train that has beds or berths for passengers to sleep in during a journey.
Something that becomes very popular or successful after initially attracting little attention.
A loanword from English, commonly used in entertainment and business contexts to describe a sleeper hit.
That movie was a sleeper hit; it became a blockbuster a few weeks after its release.
A more descriptive phrase meaning 'unexpected hit'. Can be used when the loanword feels too casual.
A spy or secret agent who lives normally for a long time until activated for a mission.
The word 寝る人 (ねるひと) only means 'a person who sleeps'. It cannot be used for a spy or an unexpected hit. Use the loanword スリーパー or the specific terms given above.
この列車には寝台車が連結されている。
This train has a sleeper car attached.
The novel became an unexpected hit and turned into a bestseller.
That new singer was a dark horse and shot to stardom overnight.
The organization is said to have placed several sleeper agents within the country.