Colloquial term for a Ph.D.
-trained individual who works as a "post-doctoral fellow" at an academic
institution or (sometimes) a company
. They are supposedly training to become professors
themselves, however there are many more post-docs than there are tenure
-track academic positions for them. Post-docing is often a transitional period
leading to getting a non-academic job in industry or becoming a writer
or any other thing you can do with a Ph.D.
At least in the academic community, post-docs are actually paid less than technicians, and are thus a cheap source of highly-skilled labour.