The phrase "fort up" is commonly used to express the act of building and strengthening one's defenses, either physically or emotionally. However, there are several synonyms for this phrase that can be used interchangeably depending on the context. "Barricade" refers to the process of blocking off an area to prevent entry or exit. "Entrench" means to establish a position, usually through digging or constructing fortifications. "Secure" can refer to both physically or emotionally protecting oneself. "Defend" means to protect oneself or someone else against attack. Finally, "hunker down" emphasizes the act of settling in for an extended period, usually in preparation for an impending threat.