dissertation
US /ˌdɪs.ɚˈteɪ.ʃən/
UK /ˌdɪs.ɚˈteɪ.ʃən/

1.
disertación, tesis
a long essay on a particular subject, especially one written as a requirement for a university degree or diploma
:
•
She spent a year writing her doctoral dissertation.
Pasó un año escribiendo su tesis doctoral.
•
His master's dissertation focused on medieval history.
Su tesis de maestría se centró en la historia medieval.