When German researchers began working on a new Latin dictionary in the 1890s, they thought they might finish in 15 or 20 years.
In the 125 years since, the Thesaurus Linguae Latinae (T.L.L.) has seen the fall of an empire, two world wars and the division and reunification of Germany. In the meantime, they are up to the letter R.
This is not for lack of effort. Most dictionaries focus on the most prominent or recent meaning of a word; this one aims to show every single way anyone ever used it, from the earliest Latin inscriptions in the sixth century B.C. to around A.D. 600. The dictionary’s founder, Eduard Wölfflin, who died in 1908, described entries in the T.L.L. not as definitions, but “biographies” of words.