An apartment building is a structure that's designed to house multiple families or individuals in self-contained living spaces. Whether you're writing a real estate listing or just looking to expand your vocabulary, there are plenty of synonyms for this common term. Some options include high-rise, multi-family dwelling, residential building, or complex. Others might refer to it as a tower, tenement, or flat building. Depending on its architectural style, you could also use descriptors like mid-century modern or Victorian era. Of course, in many cases, the word "apartment building" is perfectly clear and concise, making it a reliable choice for everyday use.