A century (from the Latin centum, meaning one hundred)'s one hundred consecutive years. Centuries are numbered ordinally in English and many other languages (for example "the seventh century AD"). Start and end in the Gregorian Calendar According to the Gregorian calendar, the 1st century AD started on January 1, 1 and ended on December 31, 100. The 2nd century started at year 101, the third at 201, etc. The n-th century started/will start on the year 100×n - 99. A century will only inclu… (More on Centennial)