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tenured graduate student: n.

One who has been in graduate school for 10 years (the usual maximum is 5 or 6): a ‘ten-yeared’ student (get it?). Actually, this term may be used of any grad student beginning in his seventh year. Students don't really get tenure, of course, the way professors do, but a tenth-year graduate student has probably been around the university longer than any untenured professor.