Wiktionary
n. A university student, usually already possessing a four year degree, who is working on a master's degree or Ph.D.
WordNet
n. a student who continues studies after graduation [syn: graduate student, postgraduate]
Usage examples of "grad student".
Reaching out, she patted the box that enclosed the body of the other grad student.
Because she was doing fieldwork while he was still a grad student, she automatically thought of herself as being more mature.
As it turned out, the guard was a grad student I knew, who let us in.
He bumped into Lane O'Hara now and then, mostly in the aquarium, but she was strictly business, a staff scooter telling a grad student which chore had to be done next.
I get paid to do this job, and I get my regular stipend as a grad student, and I'll probably get a book contract out of it too.