The fifth book of the Pentateuch is Deuteronomy, which is an 11-letter word. Deuteronomy is a book of the Hebrew Bible, also known as the Torah or the Pentateuch. It is the fifth book of the Bible and is the second part of the Deuteronomistic history, which is a biblical interpretation of the history of Israel. It contains a series of laws and regulations that were given to Moses by God on Mount Sinai. The book is divided into 34 chapters and covers topics such as the Ten Commandments, the Shema, and the Song of Moses.