一代|いちだいichidai[2]nakadaka (mid-high)

1. noungeneration; lifetime; age
   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.

• Synonym生涯しょうがいNeutralOne's whole life or career; leans formal, as in 「生涯学習」. 一代 stresses one person's or one generation's lifetime, as in 「一代で築く」.
• Synonym一生いっしょうNeutralThe everyday word for a whole life; stresses the length of time and carries no sense of a generation.
• Synonym一世いっせいWrittenA lifetime or one generation; chiefly in the set phrase 「一世一代」. Written/formal.
• Related人生じんせいNeutralLife as lived — one's course, experiences and fortunes; no generational nuance.
• Related寿命じゅみょうNeutralLifespan: how long a person or animal lives; also the service life of machines and batteries.
• Related一期いちごWrittenA lifetime; almost only in 「一期一会」, rarely alone. Written register.
• RelatedライフNeutralLoanword for life or living; mostly in compounds like 「ライフワーク」.
• Related一世いっせWrittenA lifetime or one generation; chiefly in the set phrase 「一世一代」. Written/formal.
• Related一生涯いっしょうがいNeutralOne's entire life, start to finish; heavier than 「一生」, stressing the whole span of years.
• Related生存期間せいぞんきかんWrittenThe span one stays alive; medical and statistical flavor, not used for a family business.
• Antonym永代えいたいWrittenAntonym: eternity, permanence, as in 「永代供養」 — the opposite of a single generation.
• Antonym万代ばんだいWrittenAntonym: all generations, thousands of years — the opposite of 一代's single generation.

Use 「一代」 for one person's lifetime or one generation, as in 「一代で財を築く」 or 「一代記」. For a whole life say 「一生」 or 「生涯」; for life as lived, 「人生」; for lifespan, 「寿命」. 「永代」 and 「万代」 are the opposites, meaning eternity.

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

1. 一いち代目だいめ。初代しょだい。
2. 一人ひとりの君主くんしゅや領主りょうしゅ、戸主こしゅなどがその地位ちいで支配しはいしている期間きかん。
3. 一生いっしょう。生涯しょうがい。
4. ある時代じだい。当代とうだい。
5. 事業じぎょうや家業かぎょうを継ついで主ぬしとなる期間きかん。