is a Japanese lexeme consisting of four kanji (Chinese characters). English translations of include "four-character compound", "four-character idiom", "four-character idiomatic phrase", and "four-character idiomatic compound". It is equivalent to the Chinese . Definition and classification in the broad sense refers to Japanese compound words consisting of four kanji characters. In the narrow or strict sense, however, the term refers only to four-kanji compounds that have a particular (idiomatic) meaning that cannot be inferred from the meanings of the components that make them up. Non-idiomatic There exists a very large number — perhaps tens of thousands — of four-character compounds. A great majority of them are those whose meanings can be easily deduced from the literal definition of their parts. These compounds may be called non-idiomatic . For example, the compound word is a non-idiomatic . It is made up of four characters: , , , and . Alternatively, it can be regarded as consisting of two common two-character compounds: , and . Either way, the meaning of the compound is clear; there are no idiomatic meanings beyond the literal meanings of its components. Below are a few more examples of non-idiomatic : , (, university + , education) , (, environment + , deterioration) , (, Japan + , U.S. + , relations) , (, history + , novel) , (, advertisement + , effect). Note that is itself a non-idiomatic four-character phrase. Idiomatic By contrast, several thousands of these four-character compounds are true idioms in the sense that they have a particular meaning that may not be deduced from the literal meanings of the component words. An example of the highly idiomatic compound is: , (, ocean + , thousand + , mountain + , thousand) "Ocean-thousand, mountain-thousand" means "a sly old fox" or someone who has had all sorts of experience in life so that they can handle, or wiggle out of, any difficult situations through cunning alone. This meaning derives from an old saying that a snake lives in the ocean for a thousand years and in the mountains for another thousand years before it turns into a dragon. Hence a sly, worldly-wise person is referred to as one who has spent "a thousand years in the ocean and another thousand in the mountains". Many idiomatic were adopted from classical Chinese literature. Other four-character idioms are derived from Buddhist literature and scriptures, old Japanese customs and proverbs,