自然语言（英语：Natural language）通常是指一种自然地随文化演化的语言。英语、汉语、法语、西班牙语、日语为自然语言的例子，而世界语则为人工语言，即是一种由人特意为某些特定目的而创造的语言。

不过，有时所有人类使用的语言（包括上述自然地随文化演化的语言，以及人工语言）都会被视为“自然”语言，以相对于如编程语言等为计算机而设的“人造”语言。这一种用法可见于自然语言处理一词中。自然语言是人类交流和思维的主要工具。

In neuropsychology, linguistics and the philosophy of language, a natural language or ordinary language is any language that has evolved naturally in humans through use and repetition without conscious planning or premeditation. Natural languages can take different forums, such as speech, signing, or writing. They are distinguished from constructed and formal languages such as those used to program computers or to study logic.