When it comes to synonyms for the term "sea bow", a few alternatives come to mind. One common synonym is "arch", which refers to a curved shape or structure resembling a bow. Similarly, "arc" can be used to describe a curved segment in a circle or a curved shape in general. Another alternative is "crescent", which typically refers to the shape of the moon when it is less than half illuminated. "Half-moon" is also a synonym for "sea bow", often used to depict a semi-circular shape. Lastly, the term "concave" can be used, emphasizing the inward curvature resembling the shape of a bow.