LanguageThe term for a medium of expression, which consists of a vocabulary, some semantics, and a syntax for accessing the semantics. Some of the vocabulary includes inactive subject matter while other parts are active and can operate on other terms in the vocabulary.
Programming languages are languages which are equivalent in expressiveness to Turing machines. Domain-specific languages are those whose vocabulary is related to some task or other very specific collection of activities.
It is independently possible that the components of a language, whether source domains, syntaxes, or semantics, are tightly- or loosely-coupled. Considering a collection as a whole yields a valid concept of language regardless of how counter-dependent they are; the difference lies in the utility of the language made by such a collection.