In our chapter, we describe a secret language, Fedwet, that was spoken in Ethiopia until recently. Most Ethiopians speak two or more of the 80 languages found in the country. This includes the people of the Gurage Zone in central Ethiopia, where several Ethiosemitic languages are spoken. One of these, Chaha, is the basis for Fedwet, which was spoken almost exclusively by a particular group of Gurage women, the so-called Moyet. Fedwet is no longer used because of modern education and the dominance of Christianity and Islam in the region. However, a few old women still remember words and short phrases in Fedwet. Based on previous research, our description begins with an overview of the social and cultural aspects of the Moyet. We then analyze our data on the Fedwet language that we collected from three former Moyet living in the Chaha District of the Gurage Zone. We show that Fedwet is a modified variant of Chaha. Both share the same grammatical structure, but differ in the lexicon. Apart from some borrowings from other languages, the lexical differences are mainly the result of a series of morphological, morphosyntactic, and semantic manipulations of original Chaha words, which obscure their meaning. Thus, the original Fedwet speakers, who did not have a modern education, were able to manipulate parts of their mother tongue to create a secret language that was then spoken beyond the Chaha language area and passed down through several generations. But it is now on the verge of extinction.