Chengyu

Chengyu (simplified Chinese: ; traditional Chinese: , pinyin: chéngyǔ, lit. "set phrases") are a type of traditional Chinese idiomatic expression, most of which consist of four characters. Chengyu were widely used in Classical Chinese and are still common in vernacular Chinese writing and in the spoken language today. According to the most stringent definition, there are about 5,000 chengyu in the Chinese language, though some dictionaries list over 20,000.

They are often referred to as Chinese idioms or four-character idioms; however, they are not the only idioms in Chinese.

Chengyu are mostly derived from ancient literature. The meaning of a chengyu usually surpasses the sum of the meanings carried by the four characters, as chengyu are often intimately linked with the myth, story or historical fact from which they were derived. As such, chengyu do not follow the usual grammatical structure and syntax of the modern Chinese spoken language, and are instead highly compact and synthetic.

Chengyu in isolation are often unintelligible without explanation, and when students in China learn chengyu in school as part of the classical curriculum, they also need to study the context from which the chengyu was born. Often the four characters reflect the moral behind the story rather than the story itself. For example, the phrase "break the woks, sink the boats" (,  pò fǔ chén zhōu) is based on a historical account where the general Xiang Yu ordered his troops to destroy all cooking utensils and boats after crossing a river into the enemy's territory. He won the battle because of this "no-retreat" strategy. Similar phrases are known in the West, such as "burning bridges" or "Crossing the Rubicon". This particular idiom cannot be used in a losing scenario because the story behind it does not describe a failure.

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