'''Natural-language user interface''' ('''LUI''' or '''NLUI''') is a type of [[User interface|computer human interface]] where linguistic phenomena such as verbs, phrases and clauses act as UI controls for creating, selecting and modifying data in software applications.
In [[interface design]], natural-language interfaces are sought after for their speed and ease of use, but most suffer the challenges to [[natural language understanding|understanding]] wide varieties of [[semantic ambiguity|ambiguous input]].<ref>Hill, I. (1983). "Natural language versus computer language." In M. Sime and M. Coombs (Eds.) Designing for Human-Computer Communication. Academic Press.</ref>
Natural-language interfaces are an active area of study in the field of [[natural-language processing]] and [[computational linguistics]]. An intuitive general natural-language interface is one of the active goals of the [[Semantic Web]].
Text interfaces are "natural" to varying degrees. Many formal (un-natural) programming languages incorporate idioms of natural human language. Likewise, a traditional [[keyword search]] engine could be described as a "shallow" natural-language user interface.
