Minderico, also known as Piação do Ninhou (the language of Minde), was originally a sociolect or a secret language spoken by textile producers and traders in the freguesia (civil parish) of Minde (Alcanena, Portugal). After this initial phase (18th century), Minderico began to expand its vocabulary continuously and creatively. This expansion was (and continues to be) intimately related to the socio-cultural experiences of the inhabitants of Minde. For example, names and nicknames of well-known persons from Minde and the neighbouring areas were used as lexemes to express physical or psychological characteristics, as these characteristics were salient for those persons. This method of lexical formation can be explained by the fact that Minde, due to its geographical isolation, is a small and close knit community, where everyone knows one another. Therefore, using names of persons as a means to express the characteristics associated to them was immediately understood amongst members of the speech community; this was not an obstacle to effective communication.
With the increase in vocabulary, Minderico also extended its scope of application. It began to be used not only for commercial reasons to conceal information but also in daily social contexts. Consequently, the speech community increased as well and Minderico became to be seen as a unifying identity element. From this period on, Minderico came to be used by all social groups and progressed to become the everyday language in Minde - it was used within the community as a means of communication in all social, economical, cultural, and political contexts.
Minderico does not show the characteristics of secret languages anymore: It very soon ceased to be restricted to a particular social group and was used in every context of daily life; its vocabulary is not reduced to special contexts and adapts itself continuously to the new social, economic and technical realities; contrary to secret languages, its morphosyntax is complex and different from Portuguese morphosyntax (Minderico is not a Portuguese dialect!). Minderico is not restricted to the oral informal register but it is also used in the oral formal and written register. Finally, the fact that its speakers are engaged in presenting the language beyond its borders (e.g. through music, newspaper articles, internet, small glossaries) shows clearly that Minderico is not seen as a secret language anymore.
Today Minderico risks becoming extinct, more than ever before in its history.
All speakers of Minderico are bilingual; they speak Portuguese along with Minderico. While Portuguese is the language of administration and school system, Minderico remains almost restricted to the family. But even in this private sector there is a clear pressure from Portuguese on Minderico. Most likely there are no children up to 5 years who understand or use the language today, given that school education has always been in Portuguese in the region and, subsequently, Portuguese has developed into the main means of communication even within families. There are two main reasons for shifting from Minderico to Portuguese as a home language: economic pressures and professional requirements. Moreover, the speech of Minderico adults is characterized by a kind of Portuguese-Minderico code-switching and code-mixing. The knowledge of Minderico is not very homogeneous among the inhabitants of Minde.
The Interdiciplinary Centre for Social and Language Documentation (CIDLes), an institution dedicated to the research and documentation of endangered languages in Europe and the development of language technologies for lesser-used languages, is now working on the linguistic documentation of Minderico and, together with the speech community, on its revitalization.