A defensive wall, also known as a fortification, can be described using a variety of synonyms. One option is the word barricade, which implies a structure designed to block access and protect against attacks. Another synonym is bulwark, which has a similar connotation of providing protection and defense. The term rampart also fits the bill, as it refers specifically to a defensive wall made of earth and other materials. Finally, stronghold is another synonym for defensive wall, indicating a structure that is sturdy and difficult to penetrate. All of these words convey the idea of a protective barrier, serving to keep danger at bay and safeguard those within.