the written work that represents the culmination of a student’s graduate-level research progress. The core requirement of a dissertation is that it represents original work that makes an intellectual contribution to the student’s field of study.
May also be called “thesis”, but this is usually a more appropriate term for a Master’s-level degree. That’s because a thesis refers to a report of existing knowledge (i.e., showing “mastery”) while a dissertation is expected to make an original contribution to scholarship.