When talking about the location of something or someone, the phrase "in a house" is commonly used. However, there are various synonyms that can be used to describe the same location. For instance, you could use the term "indoors" to refer to a place situated within a building. Another synonym for "in a house" could be "on premises." This phrase implies that the specific location is within the boundaries of a particular property. You could also use the phrase "within the four walls" to describe the location of something inside a house. In conclusion, using different synonyms can add variety and clarity to your writing while conveying the same message.