noun, verb · writings or drawings made on a wall or other surface, usually as a form of artistic expression

他在老房子的墙壁上创作了一幅涂鸦。

verb · to write or draw poorly or carelessly, often used as a self-deprecating term for one's own calligraphy or writing

这只是我的随手涂鸦，算不得什么艺术品。