nounnoun

nounnoun is a term used in linguistics to describe a pattern of compound nouns formed by placing one noun next to another noun, with no linking morpheme. In nounnoun constructions, the left-hand noun usually functions as a modifier that narrows or specifies the meaning of the right-hand noun, which serves as the head. The resulting unit is typically treated as a single lexical item.

In English and many other languages, noun-noun compounds are productive across domains such as materials, tools, locations, and objects. Examples include stone wall, bookcase, fire truck, water bottle, glass ceiling, and street light. In these cases the head noun (the rightmost element) determines the general category (wall, case, truck, bottle, ceiling, light), while the modifier noun provides a material, type, or function.

The morphology and syntax of nounnoun compounds can vary. Some are written as closed compounds (bookcase, stonewall), others as open compounds (water bottle, street light), and a few may be hyphenated. The semantic relationship between the two nouns is often metaphorical or attributive, describing a typical or characteristic instance of the head noun.

Cross-linguistically, noun-noun compounds show different ordering patterns and degrees of productivity. In many languages the modifier precedes the head, but some languages allow head-first orders or flexible arrangements. The term nounnoun is not a universally standardized label; it is used informally to discuss the broader phenomenon of noun-noun compounding and to distinguish NN compounds from other types such as noun-adjective or noun-verb compounds.

See also: compound noun, noun-noun compound, attributive noun.