"Blue-lilac" is a rare and unique color that's not commonly found in the natural world. However, there are several synonyms for this shade that can accurately describe it. "Periwinkle" is a popular alternative that's often used to describe hues that are a mix of blue and purple. Additionally, "lavender-blue" is another great option for those looking to describe this unique color. Other synonyms include "periwinkle blue", "lavender-lilac", and "mauve-blue". Regardless of which term is used, blue-lilac is a beautiful and captivating color that's sure to catch the eye of anyone who sees it.