The work on the dictionary, which began in 1913, has reached its final definition, "zythum", a type of fermented malt drink.
The editor, Richard Ashdowne, from Oxford University's classics faculty, said such a laborious, long-term project would never be initiated now.
"Some people really did doubt we would ever reach the end," said Ashdowne.
Dictionary entries were initially painstakingly assembled using handwritten slips. The printing process was also much slower before the arrival of computers. Researchers are also able to search source materials much more quickly, when documents have been digitised.
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The project began when Oxford historian Robert Whitwell wrote a letter to The Times calling for volunteers to help with researching this dictionary.
Whitwell's plan was to produce the medieval Latin equivalent of the Oxford English Dictionary.
After 101 years, The Dictionary of Medieval Latin from British Sources will formally close in September, the BBC reported.
It will fill an academic gap that Whitwell had identified before the First World War.
Latin had been the language of written records for medieval courts, religion, science and politics. But scholars looking at Latin documents from Britain were still having to depend on a reference book first published in the 17th Century.
He says there was a "huge feeling of satisfaction" when the dictionary was completed, but also a keen awareness of the many people who have contributed.
The completion of the dictionary had been accelerated by the arrival of computer technology, Ashdowne said.
There are also plans for the dictionary, published by the British Academy and costing 660 pounds, to be produced in a digital form.