Upstairs is a common word used to describe the higher level of a building or house, but there are several other synonyms that can be used instead of the word upstairs. These synonyms include upstairs level, upper floor, top floor, upper level, top story, second floor, mezzanine level, loft, garret, attics, elevated, high-up, and ascendant. Depending on the context, any of these synonyms can be used interchangeably with upstairs. For example, instead of stating that you are going upstairs to your bedroom, you can say that you are heading to the top floor, upper level, or second floor of your house.