noun
Refers to a hundred-year period, especially a numbered historical century such as 19世紀 or 21世紀.
彼女は19世紀のフランス文学を研究している。
She studies 19th-century French literature.
21世紀は2001年に始
The 21st century began in 2001.
noun
A broader, often rhetorical use for an age characterized by something, not necessarily a precisely counted hundred years.
その発明は通信の新しい世紀を開いた。
That invention opened a new era of communication.
noun which may take the genitive case particle 'no'
of the century; epoch-making
Used as 世紀の before a noun to praise or emphasize something as exceptionally important or memorable, as in 世紀の一戦 or 世紀の大発見.
二人の対決は世紀の一戦と呼ばれた。
The match between the two was called the fight of the century.
その化石は世紀の大発見として報じられた。
The fossil was reported as the discovery of the century.