The term 'green gradient frog' refers to a frog with a green coloration that exhibits a gradient pattern, which means the color changes gradually from one shade to another. This could be a description of a specific species of frog or a general characteristic of certain frog species. The concept of gradient coloration in animals is a form of camouflage that can help them blend into their environment. For example, some species of tree frogs have green gradients that match the leaves of the trees they live in.