A fortifier is something that provides strength, support, or protection to something else. There are several synonyms for the word fortifier that can be used interchangeably depending on the context. Some of these synonyms include reinforce, strengthen, fortify, reinforce, bolster, and buttress. These words suggest a sense of firmness, durability, and stability. They can be used to describe physical structures, such as buildings, walls, or fences, as well as more abstract concepts, such as ideas or arguments. Regardless of the specific context, synonyms for fortifier all share the common theme of providing added strength and resilience to something that might otherwise be weak or vulnerable.