- 凸面镜 tūmiànjìng convex mirrorA curved mirror with a reflective surface that bulges toward the light source, often used for car side-view mirrors or safety mirrors on sharp turns; also called a [[凸镜|凸鏡|tu1 jing4]]
- 凸面体 tūmiàntǐ convex body(geometry) a convex body or convex polyhedron
- 双凸面 shuāngtūmiàn biconvexhaving two convex surfaces, typically describing a lens