Wrapper
Code layer that wraps existing functionality to alter the API — simplify, adapt, add tracing/caching, bridge between languages.
"Wrapper library" = thin facade on top of another lib (e.g., requests is a wrapper for urllib in Python). "Language wrapper" = expose a C library to Python/Java/.NET (ctypes, JNI, P/Invoke). Close design patterns: Adapter, Facade, Decorator. Risk: too many wrapper layers hide the underlying function and worsen error messages. The "just-enough-abstraction" advice.