DEU may refer to:

• Deutsche Eislauf-Union, the figure skating governing body in Germany
• Distinct Environmental Uniform, the current uniform of the Canadian Forces, adopted in the late 1980s
• Doom Editing Utility, a software utility for the computer game Doom
• The ISO 3166-1 alpha-3 country code for Germany
• Drug Enforcement Unit, a specialised police unit
• Dokuz Eylül University, a state university located in Izmir, Turkey

The Book of Deuteronomy (from Greek Δευτερονόμιον, Deuteronómion, "second law"; , Devārīm, "[spoken] words") is the fifth book of the Hebrew Bible, and of the Jewish Torah. The Hebrew title is taken from the opening phrase Eleh ha-devarim, "These are the words..."; the English title is from a Greek mistranslation of the Hebrew phrase mishneh ha-torah ha-zoth, "a copy of this law", in , as to deuteronomion touto – "this second law".