Reduplication is the repetition of the initial sound of the word. Shouldn't it just be called "duplication"? Yeah, probably: but the technical term is "reduplication". Go figure! Reduplication is a special form of the verb in ancient Indo-European languages, such as Latin, Greek, and Sanskrit. In Greek and Sanskrit, reduplication was a common and basically systematic process. In Latin, the reduplicated verb forms are much less common, but there are a number of perfect stems that show reduplication. You need to be able to recognize them, because the process of reduplication changes the way that you search for a word in the dictionary. You have to "unduplicate" the initial sound of the word in order to find its dictionary form.