noun
three-dimensionality; solidity
Refers to the quality of having three dimensions, depth, or volume; used in art, design, geometry, and figurative contexts.
この絵は立体性に欠けている。
This painting lacks three-dimensionality.
彫刻の立体性が空間を引き締める
The solidity of the sculpture tightens the space.
三次元 is the technical term for three-dimensional space or 3D, often used in science and technology, whereas 立体性 is more about the perceived quality of depth and volume.
Compound of 立体 (three-dimensional, solid) + 性 (-ness, quality). The exact historical derivation is uncertain, but the word follows a common pattern for abstract nouns in modern Japanese.