The term "back translation" is not widely known outside of professional circles (Bible and secular translators. Here is a sercular definition:
The BT is “A process in which a text which has been translated into a given language is retranslated into SL” [source language]. (Mark Shuttleworth and Moira Cowie, Dictionary of Translation Studies, 14)
Here is my own definition:
back translation: a literal retranslation from the document in the target language back to the source language, usually for the purpose of checking the TL translation. This technique is common in tribal translation work, especially when a translation consultant is being used.
“Such back translations are by necessity highly literal, although the precise decree of literalness will vary depending on the particular feature that needs to be highlighted.” (Shuttleworth and Cowie, 15)
Ironically, even Eugene Nida, the inventor of dynamic equivalence, did literal back translations. “Dr. Nida instructed Viv to translate the first two chapters—the hardest chapters in Luke—from Tboli back into English, word for word. When they finished checking these, verse after verse, question after question, Dr. Nida turned to Vivian and said, ‘Young lady, you’ve done a splendid job.'” (Doris Fell, Lady of the Tboli, p. 97)