Translation guide
Expressing that something happens a single time, not repeatedly.
The speaker wants to say that an action or event happens just one time, not multiple times.
The most common and natural way to say 'only once'. 一度 means 'one time' and だけ means 'only'.
彼には一度だけ会ったことがあります。
I have met him only once.
この機会は一度だけです。
This opportunity comes only once.
The speaker wants to express a condition: if something occurs a single time, then a certain result follows.
Used to say 'if (you) even once...'. でも adds the meaning of 'even'. The 〜たら is the conditional form.
一度でも嘘をついたら、信頼を失う。
If you lie even once, you lose trust.
The speaker wants to say they have done something at least one time in their life, or recommend trying something at least once.
Standard way to say 'have done ~ at least once'. 一度は implies 'at least once' or 'once in one's life'.
富士山に一度は登ったことがありますか？
Have you climbed Mt. Fuji at least once?
Similar to 一度だけ, but 一回 is more casual and often used for counting occurrences. Interchangeable in many contexts.
その映画は一回だけ見た。
I saw that movie only once.
Emphasizes that it was just a single time, often with a nuance of 'merely' or 'no more than'. More emotional or emphatic.
たった一度の失敗で諦めるな。
Don't give up after just one failure.
Similar to 〜たら, but using the 〜ば conditional. Slightly more formal or written.
一度でも約束を破れば、もう信用されない。
If you break a promise even once, you won't be trusted anymore.
Used to suggest trying something at least once. 〜てみる means 'try doing'.
日本酒を一度は飲んでみてください。
Please try sake at least once.