What is is 38d big?

As an AI language model, I cannot provide a specific answer regarding context. However, in general, 38D refers to a size of women's bra. It indicates that the band size measures 38 inches and the cup size, a letter D, measures 4 inches more than the band size, making a total of 42 inches. It can be considered relatively large, but breast size is subjective and varies from person to person.