Which word describes something designed to establish forms or patterns in nature?

The word that best describes something designed to establish forms or patterns in nature is "Arabesque." This term typically refers to intricate and often symmetrical decorative patterns that are inspired by nature, especially in the context of art and architecture. Arabesques incorporate elements of natural motifs, such as plants and foliage, and they create a sense of harmony and rhythm through their repetitive designs. This concept reflects an aesthetic that is focused not just on representing nature but on creating stylized versions that highlight the beauty of these natural forms.

The other options, while related to nature in different ways, do not capture the idea of creating patterns or forms with the same specificity as "Arabesque." "Flora" refers to plant life in a general sense. "Terrain" pertains to the landscape or physical geography of an area. "Geometric," while it does relate to shapes and patterns, tends to describe forms defined by precise mathematical principles rather than those that draw inspiration from organic, nature-based designs. Thus, "Arabesque" stands out as the most fitting term for something that is designed to establish natural forms and patterns.