Eponyms are often defined as words derived from proper nouns denoting mostly persons, real or fictitious, or places, and very rarely from proper names denoting events, e.g., diesel, calepino, badminton, mackintosh, or winchester. In this chapter we take a look at several types of eponyms that enjoy the status of more or less global internationalisms or are near that status. Using material from a variety of languages (English, German, Croatian, Hungarian, Spanish, Italian, etc.), we show that, in spite of the fact they are expected to function as true friends, they as frequently turn out to be, if not false friends, then at last, not to be fully true friends. In other words, they may turn out to be deceptive cognates. False friends or false cognates are words belonging to different languages, exhibiting a certain degree of formal similarity, but accompanied by no or only partial semantic overlap. In the case of our eponyms the overlap is in most cases only partial. We intend in this chapter to show that, if approached from a somewhat unusual point of view, they can, however, turn out to be less false and/or treacherous. Our proposal is that such eponyms, just like many other false friends, could be explained, and their correct use taught, by reconstructing their metonymization paths and by highlighting the points at which they start to diverge in various languages. This strategy provides an angle on the phenomenon in question that makes teaching situations more interesting because it provides an opportunity for integrating and deepening various areas of knowledge students may already possess (apart from linguistic knowledge), and therefore exhibits a high degree of motivational potential.