Pessac (Occitan: Peçac) is a commune in the Gironde department in Aquitaine in southwestern France.It is the second-largest suburb of the city of Bordeaux and is adjacent to it on the southwest. It is a member of the metropolitan Urban Community of Bordeaux. Pessac is also home to the Montesquieu University, the Bordeaux Montaigne University, and the Institut d'études politiques de Bordeaux.