Translation guide
Describes a rare, exceptional opportunity or event that is unlikely to happen again in one's life. In Japanese, this is commonly expressed with set phrases or by emphasizing the rarity and special nature of the occasion.
To say that something is a chance that will only come once in a person's life.
The most direct and common way to say 'once in a lifetime'. It literally means 'once in a lifetime' and is used for opportunities, experiences, or events.
これは一生に一度のチャンスです。
This is a once-in-a-lifetime chance.
一生に一度の経験をした。
I had a once-in-a-lifetime experience.
To describe something that happens so rarely it might only occur once in a person's life.
Literally 'a once-in-a-lifetime event'. Used for natural phenomena, historical events, or personal milestones.
この彗星は一生に一度の出来事だ。
This comet is a once-in-a-lifetime event.
一生に一度 is the everyday, neutral way to say 'once in a lifetime'. 一期一会 carries a deeper philosophical nuance about treasuring each unique encounter and is often used in formal or traditional contexts.
A traditional concept meaning 'one time, one meeting', emphasizing that each encounter is unique and should be treasured. Often used in tea ceremony and hospitality contexts, but can apply to any special, unrepeatable moment.
この出会いは一期一会だ。
This meeting is a once-in-a-lifetime encounter.
A formal, literary phrase meaning 'one chance in a thousand years', emphasizing extreme rarity. Used for golden opportunities.
千載一遇の好機を逃すな。
Don't miss this once-in-a-lifetime golden opportunity.
Means 'rarely happens' or 'hardly ever'. It conveys the idea of something being extremely uncommon, though not necessarily literally once in a lifetime.
こんな機会は滅多にない。
An opportunity like this is once in a lifetime (lit. rarely comes around).