Someone who attends graduate and professional school for a prolonged period of time and earn multiple degrees (Ph.D. , MD, JD, MBA) without the intention of ever using their degrees. May be used derisively to describe someone who is unclear about their career intentions.
Person 1: Dude, this guy is badass, he has an MD, Ph.D., JD, and MBA degree.
Person 2: Oh yeah? Well has he ever practiced medicine, law, or worked in the business field? He's in his forties and has never worked a real job in his life. He's a degree collector.
Someone who is in school for a perpetually long time, for a scholarly degree that has no practical use in the real world. Usually describes someone who comes from a wealthy or aristocratic family since pursuing such a degree costs a lot of money and won't help the individual obtain a job. In polite societies, may be used derisely to describe someone as a "professional student".
Catherine: Ah Mr. Darcy, the last time I saw you ten years ago, you were pursuing a Philosophy Degree at Oxford. What have you been up to now?
Mr Darcy: I am attending Harvard and working on my Ph.D. in Western Mediveal Literature.
Catherine: Oh that's nice. (Mockingly) You're quite the gentleman scholar.