Wiktionary
phr. The pressure to frequently publish in academic journals in order to gain tenure or to sustain a career.
Wikipedia
"Publish or perish" is a phrase coined to describe the pressure in academia to rapidly and continually publish academic work to sustain or further one's career.
Frequent publication is one of the few methods at scholars' disposal to demonstrate academic talent. Successful publications bring attention to scholars and their sponsoring institutions, which can facilitate continued funding and an individual's progress through a chosen field. In popular academic perception, scholars who publish infrequently, or who focus on activities that do not result in publications, such as instructing undergraduates, may lose ground in competition for available tenure-track positions. The pressure to publish has been cited as a cause of poor work being submitted to academic journals.
Usage examples of "publish or perish".
And the scholastic 'publish or perish' system that has always kept professionals too busy with irrelevancies to attend to their legitimate work.
It's just a variation on 'Publish or Perish,' the battle cry of academia.