What does twelve o'clock mean?

In ancient times, a day and night was divided into twelve hours: Zi (zǐ), chou (Chou), Yin (yín), Mao (m ǐ o), Chen (chén), Si (,) and Wu (shēn).

Time is an ancient unit of time. The ancients divided a day into twelve hours, and each hour is equal to two hours now. According to legend, each time is named after the time of animals in the zodiac.

Extended data:

Twelve o'clock consists of twelve specific time nouns. People can find the source of these words from the ancient books of China in the pre-Qin period. Before the Han Dynasty, these appellations were different. Until the early Han Dynasty, China implemented the taichu calendar Law. "Twelve o'clock a day, the main branch is the subject." (Zhao Yi's Examination of Jade Cong, Volume 34) Basic stereotypes and naming. The twelve o'clock calendar is unique and has a long history. It is an outstanding contribution of the Chinese nation to the astronomical calendar of mankind and one of the splendid treasures of Chinese culture.

Baidu encyclopedia-twelve o'clock