When it comes to describing an unmarried woman, there are several synonyms for the term "single girl". Some of these include: a bachelorette, a solo female, an unattached woman, a spinster, an unwed lady, a lone female, or an individual woman. Depending on the context, some of these terms may be more appropriate than others. For example, "bachelorette" is often used to describe a woman who is actively seeking a romantic partner, while "spinster" may be viewed as outdated and carry negative connotations. Ultimately, the best synonym for "single girl" will depend on the specific situation and social norms of the culture in question.