Controlled natural languages are subsets of natural languages whose grammars and dictionaries have been restricted in order to reduce ambiguity and complexity. This may be accomplished by decreasing usage of superlative or adverbial forms, or irregular verbs. Typical purposes for developing and implementing a controlled natural language are to aid understanding by non-native speakers or to ease computer processing. An example of a widely-used controlled natural language is Simplified Technical English, which was originally developed for aerospace and avionics industry manuals.
Being constructed, International auxiliary languages such as Esperanto and Interlingua are not considered natural languages, with the possible exception of true native speakers of such languages.[3] Natural languages evolve, through fluctuations in vocabulary and syntax, to incrementally improve human communication. In contrast, Esperanto was created by Polish ophthalmologist L. L. Zamenhof in the late 19th century.
Some natural languages have become organically "standardized" through the synthesis of two or more pre-existing natural languages over a relatively short period of time through the development of a pidgin, which is not considered a language, into a stable creole language. A creole such as Haitian Creole has its own grammar, vocabulary and literature. It is spoken by over 10 million people worldwide and is one of the two official languages of the Republic of Haiti.
^Gopsill, F. P., "A historical overview of international languages". In International languages: A matter for Interlingua. Sheffield, England: British Interlingua Society, 1990.
References
ter Meulen, Alice, 2001, "Logic and Natural Language", in Goble, Lou, ed., The Blackwell Guide to Philosophical Logic. Blackwell.