二に十じっ世せい紀き

also: にじゅっせいき

に

じ

っ

せ

い

き

Meanings

1

twentieth century

Refers to the 20th century (1901–2000). Used in historical, cultural, and chronological contexts.

The twentieth century was an era of war and technological innovation.

この建たて物ものは二に十じっ世せい紀き初しょ頭とうに建たてられた。

This building was constructed in the early twentieth century.

千せん九きゅう百ひゃく年ねん代だい
千九百年代 specifically refers to the decade 1900–1909 (or loosely the 20th century), while 二十世紀 always means the full 100-year span from 1901 to 2000.

二十世紀
- にじっせいき
  Standard kanji spelling; high-frequency news term.
- にじゅっせいき
  Alternate reading; にじゅっせいき is a common colloquial variant of にじっせいき.
２０世紀
- にじっせいき
  Numerical variant common in dates, tables, and informal writing.
- にじゅっせいき
にじゅっせいき

Compound of 二十 (twenty) and 世紀 (century). The reading にじっせいき is a standard contraction of にじゅうせいき, while にじゅっせいき is a common colloquial variant.