The term "single state" can refer to a variety of different situations or conditions. Some synonyms for this phrase could include "unmarried," "unattached," "lonely," "solitary," "alone," or "individual." In the context of statehood or political boundaries, "single state" might be replaced with terms such as "independent," "sovereign," "autonomous," or "self-governing." In other contexts, synonyms could include "unique," "one-of-a-kind," "standalone," or "distinct." Ultimately, the specific synonym used will depend on the context of the sentence or passage, as well as the nuances of meaning that the writer wishes to convey.