"More decagonal" can be replaced with several synonyms. One option is "more ten-sided," which describes a shape with ten sides. Another alternative is "more decagon-shaped," which specifies that something has the geometric characteristics of a decagon. "More decagonal" can also be expressed as "more decagonal in shape," or "more decagonal in appearance," to emphasize the physical resemblance to a ten-sided figure. Finally, "more decagonal" can be substituted with "more decagonal-like," which emphasizes similarity to a decagon but allows for some variation or deviation from exact ten-sidedness. These synonyms offer flexibility in description while retaining the essential meaning of "more decagonal".