A mixed language is a language that arises among a bilingual group combining aspects of two or more languages but not clearly deriving primarily from any single language. It differs from a creole or pidgin language in that, whereas creoles/pidgins arise where speakers of many languages acquire a common language, a mixed language typically arises in a population that is fluent in both of the source languages.

Because all languages show some degree of mixing by virtue of containing loanwords, it is a matter of controversy whether the concept of a mixed language can meaningfully be distinguished from the type of contact and borrowing seen in all languages. Scholars debate to what extent language mixture can be distinguished from other mechanisms such as code-switching, substrata, or lexical borrowing.