Fine structure refers to the microscopic details of the physical world, and it can be described by a variety of synonyms. Some of the words that can be used to refer to fine structure include minute, delicate, intricate, subtle, and nuanced. Each of these words conveys a slightly different shade of meaning, but they all suggest that the fine structure is complex and worthy of close attention. Other synonyms that may be appropriate for discussing fine structure might include detailed, precise, intricate, or complex. Regardless of the word chosen, the concept of fine structure is central to our understanding of the physical universe.