立体 (rittai) means “three-dimensional object”

More examples

この作品は光の当て方で立体に見えます。ko no saku hin wa hikari no a te kata de rit tai ni mi e ma su

This work looks three-dimensional because of the way the light falls on it.

Refers to something with width, height, and depth that occupies space rather than lying on a flat surface.

立体物rittaibutsu: A concrete object that has width, height, and depth and occupies space.

平面上の形ではなく、奥行きや厚みを持つ物体。hei men jō no katachi de wa na ku oku yu ki ya atsu mi o mo tsu but tai

立体 (rittai) combines 立 (ritsu, "stand") and 体 (tai, "body"), forming a compound for a body or form that stands in space.

立体 (rittai) appears in 立体交差 (rittai kōsa), where roads pass over or under one another at different levels.