Streszczenie:
In the article the term heterosemy is used with a view to historical linguistics. Properly speaking, it denotes the presence of various meanings in etymologically identical words at different stages of the development of the Bulgarian language. In diachronic aspect, the establishment of heterosemy as the main criterion for identification and description of the so-called false friends of the translator from Old Bulgarian into Modern Bulgarian language is discussed. There are different arguments adduced for the usefulness and necessity of a special study with the help of the tools of analysis in lexicography of the etymologically identical words with dissimilar semantic structure during the different periods of the history of the Bulgarian language.
