The Hebrew name of the book is 'elleh haddebarim, which are the first two words of the book, "these are the words."
The English name Deuteronomy derives from the Septuagint via the Latin Deuteronomium, meaning "second law." The translators of the Septuagint — drawing upon Deut 17:18 in which the king was commanded to make "a copy of this law" — mis-understood it to mean the book as a repetition of the book of Exodus.
Unfortunately, this mistake continues with many people conceiving the book of Deuteronomy as just another restatement of the book of Exodus. The book of Deuteronomy is actually quite a unique book of singular importance of its own.
Low Chai Hok
©Alberith, 2013