How to say "lifetime" in Japanese

• 寿命じゅみょうJLPT N2approx.Common
  nounThe expected length of life: how long a person or animal is likely to live, or a machine keeps working. Not used for one's whole life as a span of experiences.
  これらの発見はっけんのおかげで人間にんげんの寿命じゅみょうが以前いぜんの２倍ばいになった。↗

  Thanks to these discoveries, man's life span has become twice as long as before.
• 生涯しょうがいCommon
  nounOne's whole life taken as a span of years, as in 'during one's lifetime'; it can also refer to a career or working life. This is the word for 'lifetime' in that abstract sense.
  叔母おばは幸しあわせな生涯しょうがいを送おくった。↗

  My aunt lived a happy life.
• 終身しゅうしんCommon
  prenominal modifier, nounEssentially a modifier: it stands before another noun to mean 'for life' or 'lifetime', especially of statuses or arrangements lasting until death. Not used on its own for 'a lifetime'.
• 一世いっせいCommon
  nounPrimarily 'generation': the people living at one time, or the span of one generation. Its 'lifetime' sense equates a person's life with a generation, so it is seldom the word you want for 'lifetime'.
• 一代いちだいCommon
  nounChiefly 'generation' or an age or era; it can also mean one person's whole life, but for the ordinary noun 'lifetime' it is rarely the word you want.
  その仕事しごとは一いち代だいでは成し遂なしとげられないだろう。↗

  It seems the task will not be accomplished in our generation.

Use 寿命 for a lifespan—how long a person or thing lives or works—生涯 for one's whole life as a span or a career, 終身 for 'for life' before a noun, and 一世 and 一代 chiefly for 'generation'.

Usage comparisons are AI-assisted and cross-checked by multiple models; for study reference only

• 寿命じゅみょうlifespan
• 生涯しょうがいlife
• 終身しゅうしんlifelong
• 一世いっせいgeneration
• 一代いちだいgeneration
• ライフタイムlifetime
• 一生涯いっしょうがいlifetime
• 生存期間せいぞんきかんlifetime
• 畢生ひっせいlifetime
• 世よlife
• 命いのちlifetime