[efitz]

No, an API is a contract. Just like an object or a class or a structure is not a DSL. None of these modify the syntax or keywords of the language used to implement them, and only objects and classes actually have the ability to override operators.

Just grouping things together in a particular order and giving the group a name does not make a DSL.

[vidarh]

The API creates a language just the same modifying syntax, by introducing new words with new meaning.

The point is that however you want to group it, the effect is the same: You introduce a whole new vocabulary that you need to learn the rules of.