Language-agnostic
Language-agnostic programming or scripting is a software paradigm in which no particular language is promoted.
In introductory instruction, the term refers to teaching principles rather than language features.
For example, a textbook such as Structure and Interpretation of Computer Programs is really a language-agnostic book about programming, and is not about programming in Scheme, per se.
As a development methodology, the concept suggests that a particular language should be chosen because of its appropriateness for a particular task, and not purely because of the skill-set available within a development team.
For example, a language agnostic Java development team might choose to use Ruby or Perl for some development work, where Ruby or Perl would be more appropriate than Java.
"Cross-language" in programming and scripting describes a program in which two or more languages are used to good effect within a program's code, with each contributing its distinctive benefits.