The word "unposed" is commonly used to describe a natural, unforced moment, but there are numerous synonyms that can convey different aspects of this idea. "Spontaneous" is perhaps the most common synonym, suggesting a moment that was unplanned but authentic. "Natural" and "unaffected" both suggest a lack of artificiality or unnatural behavior. "Casual" can indicate a relaxed or easygoing attitude, while "unrehearsed" emphasizes the lack of preparation. Other words that may be used as synonyms include "unplanned," "unconstrained," "impromptu," and "organic." Each nuance of these synonyms can help to capture the subtle differences in meaning of the concept of being unposed.