What does SS stand for on sewing?

In sewing, "SS" typically stands for "sister seam," which refers to a type of seam that is sewn with a specific stitch type or technique, such as a straight stitch or zigzag stitch. It can also denote "seam allowance" in some contexts, indicating the space left between the stitched line and the fabric edge. Understanding the meaning of "SS" can help in following sewing patterns and instructions accurately.