The terms "dynamic equivalence" and "formal equivalence" are associated with the translator Eugene Nida, and were originally coined to describe ways of translating the Bible, but the two approaches are applicable to any translation.
Because dynamic equivalence eschews strict adherence to the original text in favor of a more natural rendering in the target language, it is sometimes used when the readability of the translation is more important than the preservation of the original wording. Thus a novel might be translated with greater use of dynamic equivalence so that it may read well, while in diplomacy the precise original meaning may be the uppermost consideration, favoring greater adherence to formal equivalence.
Completely unambiguous formal translation of larger works is more goal than reality, if only because one language may contain a word for a concept which has no direct equivalent in another language. In such cases a more dynamic translation may be used or a neologism may be created in the target language to represent the concept (sometimes by borrowing a word from the source language).
The more the source language differs from the target language, the more difficult it may be to understand a literal translation. On the other hand, formal equivalence can sometimes allow readers familiar with the source language to see how meaning was expressed in the original text, preserving untranslated idioms, rhetorical devices (such as chiastic structures in the Hebrew Bible), and diction.
Translators of the Bible have taken various approaches in rendering it into English, ranging from an extreme use of formal equivalence, to extreme use of dynamic equivalence.Extensive use of formal equivalence