Pectinal is an uncommon word, and finding synonyms for it can be a bit tricky. However, some possible alternatives include pectinated, comb-like, ridged, grooved, serrated, scalloped, toothed, wavy, meandering, and undulating. These words describe similar physical features, such as ridges or waves, which are reminiscent of the pecten, a feather-like structure found in the eyes of some animals. Pectinal can also be used to describe something that is ornamental or decorative, so synonyms for this sense might include embellished, adorned, fancy, or decorative. Whether you're talking about biology, design, or architecture, there are plenty of ways to describe something that is pectinal.