What is the Greek word for in letters?

There isn't one single Greek word that perfectly translates to "in letters." The best translation depends on the context. Here are a few options, with explanations:

* γράμμασιν (grammasin): This is the dative plural of γράμμα (gramma), meaning "letter" (as in a character of an alphabet). It would be used if you mean "in writing," "in the written form," or "by means of letters." For example, "He wrote it in letters" might be ἔγραψε αὐτὸ γράμμασιν (égraphe auto grammasin).

* ἐπιστολαῖς (epistolais): This is the dative plural of ἐπιστολή (epistolē), meaning "letter" (as in a written communication). This would be appropriate if you're referring to "in letters" meaning "via correspondence."

* βιβλίοις (bibliōis): This is the dative plural of βιβλίον (biblion), meaning "book" or "scroll." This would be appropriate if referring to something written in a book or scroll.

To choose the correct word, you need to provide more context. What is being done "in letters"?