manifold
Technical term in mathematics for a topological space that locally resembles Euclidean space.
多様体の概念は微分幾何学で重要です。
The concept of a manifold is important in differential geometry.
algebraic variety
Compound of 多様 (tayō, 'diverse') and 体 (tai, 'body'), likely a calque from English 'manifold' or German 'Mannigfaltigkeit'.