The Middle English Dictionary is a dictionary

Dictionary

A dictionary is a collection of words in one or more specific languages, often listed alphabetically, with usage information, definitions, etymologies, phonetics, pronunciations, and other information; or a book of words in one language with their equivalents in another, also known as a lexicon...

 of Middle English

Middle English

Middle English is the stage in the history of the English language during the High and Late Middle Ages, or roughly during the four centuries between the late 11th and the late 15th century....

 published by the University of Michigan

University of Michigan

The University of Michigan is a public research university located in Ann Arbor, Michigan in the United States. It is the state's oldest university and the flagship campus of the University of Michigan...

. "Its 15,000 pages offer a comprehensive analysis of lexicon and usage for the period 1100-1500, based on the analysis of a collection of over three million citation slips, the largest collection of this kind available."

The project began in the 1920s. The first major edition of the Middle English Dictionary was published by Hans Kurath

Hans Kurath

Hans Kurath was an American linguist of Austrian origin. He was full professor for English and Linguistics at the University of Michigan, Ann Arbor...

and Sherman Kuhn in 1954. Expansions were published in numerous volumes over the next several decades. It was completed in 2001. In 2007 the full dictionary was made freely available and searchable online in an HTML format. The home page for searching the dictionary is http://ets.umdl.umich.edu/m/med/.