- The century that began on January 1, 1900, and ended on December 31, 1999. Approximately equal to the twentieth century.
- (rare) The decade that began on January 1, 1900 and ended on December 31, 1909. The noughties.
|21th century||2000s - 2010s - 2020s|
|20th century||1900s - 1910s - 1920s - 1930s - 1940s - 1950s - 1960s - 1970s - 1980s - 1990s|
|19th century||1800s - 1810s - 1820s - 1830s - 1840s - 1850s - 1860s - 1870s - 1880s - 1890s|
|18th century||1710s - 1720s - 1730s - 1740s - 1750s - 1760s - 1770s - 1780s - 1790s|
|Previous||1000s - 1010s - 1020s - 1030s - 1040s - 1050s - 1060s - 1070s - 1080s - 1090s|
|Decade only||00s - 10s - 20s - 30s - 40s - 50s - 60s - 70s - 80s - 90s|
|'00s - '10s - '20s - '30s - '40s - '50s - '60s - '70s - '80s - '90s|
|00's - 10's - 20's - 30's - 40's - 50's - 60's - 70's - 80's - 90's|
|aughts/noughties/oughts - oneties/tens/teens - twenties - thirties - forties - fifties - sixties - seventies - eighties - nineties|
|Nicknames||Gay Nineties - Naughty Nineties - Dirty Thirties - Roaring Twenties|