凸

• Pinyin: tū
• Hanzi breakdown: 凸 — pictograph of a protruding shape

Meaning

Convex; protruding; raised; bulging out.

Describes a surface that curves or bulges outward, opposite of concave (凹). Used in optics (凸透镜 convex lens), geography (凸岸 convex bank), and general descriptions of shapes.

Examples

1. 凸透镜可以聚焦光线，用来点火或者放大。 Convex lenses can focus light, used for starting fires or magnification.
2. 地面上有几块凸起的石头，走路要小心。 There are some protruding stones on the ground — watch your step.
3. 这款键盘的键帽是凸面设计，手感很舒服。 This keyboard has convex keycaps — the feel is very comfortable.

Usage Guide

Context: shapes, optics, descriptions

Tone: technical

Do Say

• 凸透镜。(Convex lens.)
• 凸起。(Protrusion.)

Don't Say

• 把'凸'和'凹'搞混 (凸 is convex/protruding — 凹 is concave/indented; don't confuse them)

Origin & History

Pictograph depicting something protruding upward.

Cultural Context

Generation: All ages

Social background: Universal