Exact Answer: 10 Years
Decade became a part of the English vocabulary in 1590 officially. It is significantly used to refer to every ten years in a century. For instance, the 1680s or 1930s, which denotes the time between 1680-1689.
In the Georgian calendar, decades denote different periods. Their calendar has no zero meaning that if you are mentioning the 1850s, it is the period between 1851- 1860.
The difference between the Georgian calendar and the standard calendar is seen when determining specific decades in a century. For instance, usually, the eighties refer to the years between 1980-1989. But in the Georgian calendar, the 190th decade is between 1981- 1990.
How Long is a Decade?
The use of decades to symbolize ten years period has enabled humanity to distinguish significant historical events easily. Decades have allowed human beings to quickly identify specific past events, for example, the 40s or 30s, which means the 1940s and 1930s, respectively.
Each decade has a nickname derived from significant events that occurred during that period. A suitable example in US history is the ‘roaring twenties,’ which refers to the period in the 1920s during which a lot of cultural change and economic growth took place.
Most historical occurrences are divided in decades, therefore, making it easier for people to distinguish events that occurred during a specific time in the past.
Other than historical events, age can also get classified into decades. Below is the classification of ages in their specific decades;
| Name of the period | Number of Years it covers | Someone in their |
| Denarian | 10-19 | – |
| Vicenarian | 20-29 | The 20s |
| Tricenarian | 30-39 | The 30s |
| Quadragenarian | 40-49 | The 40s |
| Quinquagenarian | 50-59 | The 50s |
| Sexagenarian | 60-69 | The 60s |
| Septuagenarian | 70-79 | The 70s |
| Octogenarian | 80-89 | The 80s |
| Nonagenarian | 90-99 | The 90s |
| Centenarian | 100 and above | – |
The term decade has also been used to identify the period in the 1990s when Japan’s economic market collapsed. The period was known as the lost decade, which occurred just after the second world war.
The economic crash occurred when the Finance Minister increased interest rates. The increase in prices led to the failure of the stock market, which affected the country’s economic growth.
The crisis lasted for almost a decade, and currently, it still affects the Japan business market.
Other terms used in the calendar
Century, which is a period of a hundred years, for example, the 19th century. The 19th century marks the years between 1901-2000. A period lasting for 200 years is a bicentennial.
- Millennium, it is used to term 1000 years.
- Megaannum, it is used to describe one million years.
- A period of 2 weeks is a fortnight
- A score is 20 years, while a lustrum is for five years.
- A short span of 2, 3, or 4 years gets termed as a biennium, triennium, and quadrennium, respectively.
Why is Decade 10 Years Long?
The word decade is derived from the Greek word ‘dekas,’ meaning a group of ten. The word decade was used by the Romans, who used the syllable dec- to identify items grouped in tens: E.G., decathlon, decagon. The two terms describe a collection of ten things. The word dec- was, therefore, incorporated into the calendar to show the timing of 10 years.