The definition of a dissertation is a lengthy and formal thesis.
An example of a dissertation is a paper that someone writes to complete her Ph.D. program.
a formal and lengthy discourse or treatise on some subject, esp. one based on original research and written in partial fulfillment of requirements for a doctorate
Origin of dissertationLate Latin dissertatio from Classical Latin dissertare, to discuss, argue, frequentative of disserere from dis-, apart + serere, to join: see series
A lengthy, formal treatise, especially one written by a candidate for the doctoral degree at a university; a thesis.
From Latin dissertātiō, dissertātiōnem, from dissertare.