With 6,400 entries, this is the most complete available lexicon of ancient Sumerian vocabulary. It replaces version 3 of the author's Sumerian Lexicon, which has served an audience of over 380,000 visitors at the web site www.sumerian.org since 1999. This published version adds over 2,600 new entries, and corrects or expands many of the previous entries. Also, following the express wish of a majority of online lexicon users, it has merged together and sorted the logogram words and the compound words into purely alphabetical order. This book will be an indispensable reference for anyone trying to translate Sumerian texts. Also, due to the historical position of ancient Sumer as the world's first urban civilisation, cultural and linguistic archaeologists will discover a wealth of information for research.