A system of signs for expressing thought. The system can be either natural or artificial, i.e. something that emerges gradually as a cultural artifact or something that is intentionally created by a person or group of people.
||constructed language||An ConstructedLanguage is a HumanLanguage that did not evolve spontaneously within a language community, but rather had its core grammar and vocabulary invented by one or more language experts, often with an aim to produce a more grammatically regular language than any language that has evolved naturally. This Class includes languages like Esperanto that were created to facilitate international communication.|
| ||manual human language||A ManualHumanLanguage is a HumanLanguage which has as its medium gestures and movement, such as the shape, position, and movement of the hands.|
| ||natural language||The subclass of HumanLanguages which are not designed and which evolve from generation to generation. This Class includes all of the national languages, e.g. English, Spanish, Japanese, etc. Note that this class includes dialects of natural languages.|
| ||spoken human language||A SpokenHumanLanguage is a HumanLanguage which has as its medium the human voice. It can also be represented visually through writing, although not all SpokenHumanLanguages have a codified written form.|
| ||WrittenHumanLanguage||The form of a HumanLanguage used in Writing. Not all HumanLanguages have a written form. There may be forms of a language in written form that are radically different for the same spoken form, i.e. Pinyin and written Chinese.|