What does USD, MSD, SD etc. mean when referring to BJDs? I hear the acronyms tossed around on websites and YouTube videos referring to dolls and doll clothes.
SD and MSD are used to refer to the scale of the dolls. SD is 1/3 scale (about 60cm) and MSD is 1/4 (about 40-45cm). There is also YoSD that is about 1/6. The smaller dolls tend to have more childish proportions and features, but not always. The acronyms actually stands for "Super Dollfie" and "Mini Super Dollfie" and that is what one of the earliest companies that made the kind of dolls that is now known as ABJD (asian ball jointed doll) called their dolls in different sizes and the names kind of stuck. Now SD and MDS are used to tell the size of the same type of dolls from other companies as well. As you have noted it is also used to roughly tell the size and scale of doll accessories, such as wigs, clothes, furniture etc.