What is "all but dissertation"

n. (context academics English) See ABD.

"All but dissertation" (ABD) is a mostly unofficial term identifying a stage in the process of obtaining a research doctorate in the United States and Canada. In typical usage of the term, the ABD student has completed only the required preparatory coursework, and passed any required preliminary and comprehensive examinations, but has not completed the research requirements, typically including the writing and defense of a dissertation.