A person who is not a resident or member of a particular institution, especially a school or college, but who is allowed to attend classes or participate in activities.

As an extern, she was able to attend lectures at the university without being enrolled as a full-time student.

externadjektiv

Situated or occurring on the outside; external.

The extern surface of the building was covered in ivy.

Relating to or involving outside matters or influences.

The extern factors affecting the project were beyond our control.

In computing, designating a variable or function that is defined in another translation unit, typically flagged with the keyword "extern".

In C, an extern declaration tells the linker that the variable exists in a different source file.