The article presents the functional history of one of the foreign-language roots borrowed by Russian in the XVIII century. The French root fl anc- gave rise to a group of words derived from фланг- and фланк- in Russian. Using the material of the dictionaries and the changes in word usage some regular properties of the semantic development is shown for this derivational group against the background of the general language processes in the fi eld of lexicon for a more than 200-year period. The history of the borrowed root fl anc- in Russian is marked by discrepancies between differently formed loan-words, heterogeneity of their derivational sources from the point of view of relevance for native speakers, and a sporadic revival of the archaized meanings in the context of language contacts and bilingualism. The similar destiny is far from being single.