ENAs it has been established by scholarship, Sirvydas based the second version, namely, the second edition and the subsequent posthumous editions of his dictionary, on the first edition of the Polish-Latin-Greek lexicon titled Thesaurus Polonolatinograecus and compiled by Gregorius Cnapius (in modern Polish known as Grzegorz Knapski; 1561?–1638). Scholarly comparison of Cnapius’ and Sirvydas’ dictionaries has revealed that Sirvydas borrowed the list of Polish and Latin headwords from Cnapius with some alterations and wrote the Lithuanian part. It was also established that Elger likewise based his dictionary on that of Sirvydas, from which he borrowed the Polish and Latin word list, and wrote the Latvian equivalents. The first scholar who pointed out this fact was Daina Zemzare in 1961. Later other scholars argued that Elger’s dictionary was based not only on Sirvydas’ work, but also on that by Cnapius, which, as mentioned above, was Sirvydas’ source of Polish and Latin headwords. Furthermore, Gintarė Judžentytė and Vilma Zubaitienė studied the evolution of scholars’ views in terms of how Elger’s dictionary was compiled. In their presentation of findings at the conference on the history and dialects of Baltic languages in November 2014 Judžentytė and Zubaitienė also accepted the view that Elger’s dictionary was based not only on Sirvydas, but also on Cnapius. However, this conclusion needs to be addressed and revised. There are no dictionaries without errors; some errors have crept into Sirvydas’ dictionary as well. Naturally, Elger could not use the erroneous material found in Sirvydas for his own dictionary. It seems to be a reasonable assumption that upon noticing an error, Elger must have corrected it in some way.It should not be understood that Sirvydas’ dictionary was faulty; on the contrary, it was an excellent dictionary: in its nearly fifteen thousand entries there are very few errors. However, in works of such complexity some errors are inevitable. By all likeness the errors have occurred due to the typesetter’s negligence. As manifested by the entirety of his dictionary, Sirvydas was a competent scholar and would not have let obvious slips remain uncorrected; but the third edition of Sirvydas’ dictionary was published post-humously in 1642, and the previous, second edition was published the same year Sirvydas died, so apparently, in the terminal months of his life, he did not have an opportunity to do proper proofreading. [p. 71] Keywords: Sirvydas, Elger, Cnapius, lexicography, Latin.