時代|じだいjidai[0]heiban (flat)

1. nounperiod; epoch; era; age
   今いまや時代じだいとの競争きょうそうになった。↗

   It was now a race against time.
2. nounthe times; those days
3. nounoldness; ancientness; antiquity
4. nounantique; period piece

• SynonymエポックWrittenWritten loanword for a groundbreaking new era; mostly seen in 「エポックメイキング」 rather than on its own.
• Synonym時世じせいWrittenWritten word for the state of the world at a given time, usually 「ご時世」, often with a sighing, rueful tone.
• Synonym年代ねんだいNeutralNeutral word for a period, as in 「1990年代」; it can mean an era too, but its focus is on time marked off in units of years.
• SynonymエイジNeutralNeutral loanword for age or period; it turns up mostly in compounds such as 「ニューエイジ」.
• Related時期じきNeutralNeutral word for a stretch of time or the right moment, as in 「この時期」; covers a shorter span than 「時代」.
• Related期きWrittenWritten word for a period or term, used mostly as a suffix in words like 「第一期」 and 「学期」.
• Related期間きかんNeutralNeutral word for the span between two points in time, as in 「有効期間」; it measures duration, not an era.
• Related世紀せいきNeutralNeutral word for a span of one hundred years, as in 「二十一世紀」; it can also loosely mean a long age, but its core use is the century as a unit.
• RelatedスパンNeutralNeutral loanword for a length of time, as in 「長いスパンで考える」; it describes how long a period lasts rather than naming an era.

Use 「時代」 by default for historical eras and ages. Pick 「時期」 for a stretch of time or the right moment, 「期間」 for a span between two points, 「年代」 for year-based divisions, 「世紀」 for a hundred years, and 「ご時世」 for the state of the world. 「スパン」 talks about how long a span is, and 「エポック」「エイジ」 mostly appear in compounds.

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

1. 進行中しんこうちゅうの時間じかん区分くぶんである現在げんざい。
2. 歴史れきし上じょうや人生じんせいの中なかでのある時期じきなど、長期ちょうきの時間じかんをある共通きょうつうする観点かんてんで分別ぶんべつした区分くぶん。