A human written or spoken language used by a community; opposed to e.g. a computer language WordNet 3.0 & Open English WordNet

In neuropsychology, linguistics, and philosophy of language, a natural language or ordinary language is any language that occurs naturally in a human community by a process of use, repetition, and change without conscious planning or premeditation. Wikipedia

Language naturally spoken by humans, as opposed to "constructed" and "formal" languages Wikidata

A language which has developed over time as a result of the innate human ability for language. OmegaWiki

Any human language that has evolved naturally in a community, usually in contrast to computer programming languages or to artificially constructed languages such as Esperanto. Wiktionary

Human language developed naturally. Wiktionary (translation)