1. The names of the book, משנה/Mishneh, Δευτέρωσις/Deuterosis, Δευτερόνομος/Deuteronomos, ספר תוקחות, Sepher Tokahoth.
The fifth book of Moses is called Δευτερονόμιον/Deuteronomy, ἐπειδὰν μετὰ τὰ γεγραμμένα, ἐν ταῖς πλαξὶ, δεύτερον ὥσπερ νόμον τοὺς λόγους τοῦ βιβλίου τούτου ἐλάλησεν ὁ Μωυσῆς τῷ Ἰσραὴλ ἐκ προστάγματος κυρίου, because, after the law was received written on tables, by the precept of God Moses delivered to Israel the sermons of the present book as a second law, as Saint Athanasius says in his Synopsi Scripturæ. In which place he also produces a second reason, because in this book Moses δευτεροῖ καὶ διεσάφησε, repeats and declares, whatever had been said beforehand in Exodus, Leviticus, and Numbers, all things lawful, cleansings and precepts, and urges the people to the observance of them. Namely, since those that were born in the desert did not hear the first promulgation of the law, it pleased Moses באר, to explain, again (Deuteronomy 1:5[1]) both the past events and the law previously delivered, with the addition of some new things, so that those also, not only by simple writing, and with the same repeated, but also by hearing from the mouth of Moses, might learn matters of such moment. Hence, therefore, that book was called מִשְׁנֶה/Mishneh/copy, δευτέρωσις/deuterosis, second rank, δευτερόνομος/deuteronomos, second law, especially δευτερονόμιον/ Deuteronomy, by the term from Deuteronomy 17:18, in which מִשְׁנֵ֙ה הַתּוֹרָ֤ה, Mishneh Torah, the copy of the law, which the King sitting on his throne is commanded to write in a volume, is translated δευτερονόμιον/Deuteronomy by the Septuagint, and Deuteronomium by the Vulgate. By the Hebrews it is entitled אלה הדברים, Elleh haDebharim, these are the words, from its initial words, andספר תוקחות, Sepher Tokahoth, book of rebukes, from chapter 28, in which the rebuke and punishments of the transgressors of the law are described.
[1] Deuteronomy 1:5: “On this side Jordan, in the land of Moab, began Moses to declare (בֵּאֵר) this law, saying…”