What does "Publish or perish" really mean?
For graduate students, it means "Publish or you won't get an academic job."  In many parts of academia, not getting an academic job is considered equivalent to death.

For assistant professors, if means "Publish or you won't get tenure."  In many parts of academia, not getting tenure is considered equivalent to death.


  Lastly, is it possible to be a researcher without concerning about "Publish or perish"?


Sure, of course.

If you're publishing.