The geographical term for the transition zone between the desert and grassland is called a semi-arid region or bushland. These areas typically exhibit a mix of vegetation, where arid conditions gradually give way to more lush grasses and shrubs. Such regions may be found in several parts of the world, often serving as vital ecosystems for various plant and animal species. Understanding these zones is critical for ecology and land management, as they play essential roles in climate regulation and biodiversity.