What's Chengyu?

Chengyu (Chinese: 成语, pinyin: chéngyǔ ) are a type of traditional Chinese idiomatic expressions, most of which consist of four characters. Chengyu were widely used in Classical Chinese and are still common in modern Chinese writing and in the spoken language today. There are about 5,000 chengyu in the Chinese language according to the most stringent definition, 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 to modern Chinese, 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" (破釜沉舟, 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.

破釜沉舟, pò fǔ chén zhōu

However, that is not to say that all chengyu are born of an oft-told fable. Indeed, chengyu which are free of metaphorical nuances pervade amidst the otherwise contextually driven aspect of written Chinese. An example of this is "speaking, yet without trust" (言而无信, yán ér wú xìn), referring to an individual who cannot be trusted despite what he says, an essentially deceitful person. The idiom itself is not derived from a specific occurrence from which a moral may be explicitly drawn; instead, it is succinct in its original meaning and would likely be intelligible to an individual learned in formal written Chinese. Its archaic nature is only betrayed by the now-unusual use of the character yán () as a verb.

A good news is that many Chinese idioms have their English equivalents which could help western learners memorize. For example, 冰山一角(bīnɡ shān yì jiǎo) and "the tip of the iceberg" share both their literal and idiomatic meanings. 

冰山一角--bīnɡ shān yì jiǎo

Chinese idioms can also serve as a guide through Chinese culture. Chengyu teach about motifs that were previously common in Chinese literature and culture. For example, idioms with nature motifs – e.g., mountains (山, shān), water (水, shuǐ), and the moon (月, yuè) – are numerous. Works considered masterpieces of Chinese literature – such as the Four Great Classical Novels – serve as the source for many idioms, which in turn condense and retell the story.

How to learn Chengyu?

Here're some methods which will help you to learn chengyu:

1. try to understand the meaning of every character

2. sum up the meaning of every character 

3. know the background knowledge of chengyu

4. find a English equivalent

5. write a small phrase in English to describe it if there's no English equivalent.