What is a postdoctoral fellow?
An individual who has received a doctoral degree (or equivalent) and is engaged in a temporary and defined period of mentored advanced training to enhance the professional skills and research independence needed to pursue his or her chosen career path.
NIH/NSF definition approved January 2007
(applies to all postdoctoral scholars whether supported on fellowships or research grants)
Additional resources explaining what it means to be a postdoctoral fellow:
Publications About Postdocs
Websites for Postdocs