Dynamic and formal equivalence are concepts from linguistics.

When a language is translated into another one, there is a problem: the meaning of a word or a phrase in the first language is not the same as that of the word or phrase in the second language. The first language may also have words, phrases or grammatical structures that do not exist in the second language.

There are two possible ways to solve this problem:

1. The translator can look at what the text means. He or she can then try to find expressions in the target language that mean very similar things. With this approach, the translation will sound more natural, and may be easier to read. This approach towards translation is known as dynamic or functional equivalence.
2. It is possible to make a literal translation. The approach towards this kind of translation is called formal equivalence. A literal translation may mean that the text is translated word-for-word. This will be harder to read, but it will be closer to what is written in the source text. However, there may even be some expressions in the source language that are absent in the target language. In that case, they are used in the translated text just the way they have been in the source text. But only the letters used in the source language for those expressions are replaced with letters from the target language. And it is done in such a way that the expressions used in the translation sound similar to those in the source text.

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