Idealism is a belief system that advocates for the pursuit of perfection and the attainment of the highest aspirations. The antonyms of unidealistic would be pragmatic, realistic, practical, and down-to-earth. These terms indicate a focus on the tangible and the achievable, rather than an emphasis on lofty goals and abstract principles. A pragmatic approach is more concerned with what works in reality, rather than what appears perfect in theory. A realistic outlook acknowledges the limitations of the current situation and seeks to find workable solutions. A practical attitude prioritizes usefulness and effectiveness, rather than pure idealism. Finally, a down-to-earth perspective is grounded in a practical, realistic understanding of the world.