Since 1898, Bosworth-Toller's Anglo-Saxon Dictionary has been the primary lexical reference for study of the Anglo-Saxon language. This huge dictionary is based on the manuscript collections of Joseph Bosworth, edited and enlarged by T. Northcote Toller. It is perhaps the most comprehensive dictionary of the English language ever published. This Old English Dictionary is out of print, hard to find, and expensive. It's also huge and not that fast to look up words in, especially as one must check both the original dictionary plus several supplements.