Dwarfdom is a fairly obscure term, so there aren't many common synonyms that would work as a direct replacement. However, there are a few related words and phrases that could be used depending on the context. For example, if you're talking about fairy tales or fantasy, you might use the term "dwarf kingdom" instead. Alternatively, you could use the word "shortness" to describe a group of people who are all dwarfs, or "vertically challenged" as a more polite option. Other options might include "smallness" or "diminutiveness," depending on the tone and purpose of the text.