 Welcome to another unit. Perhaps you already know that reduplication comes from Latin reduplicatio, meaning doubling, folding. It is the act or result of doubling a sound word or word element, usually for grammatical or lexical purposes. It is one of the most common natural processes of forming compound words. This unit outlines the principles of reduplication in general and its realization in present-day English in particular. In the virtual session, we will first exemplify reduplication in general using several languages as well as particular stages of language mastery, for example child language. Additionally, we will look at reduplication in present-day English. If you don't know where to start, well, use this question sheet with its hyperlinks as default guidance. The mastery worksheet is a dynamic multiple-choice task with several questions about reduplication. It should be easy to answer after the virtual session. Well, and as usual, the practical provides you with data from several languages ready for analysis. And it also asks you to look at some selected languages to find out how they realize reduplication. Quite a challenging unit, but we're sure that you will like it.