Compound (linguistics

In linguistics, a compound is a lexeme (a word) that consists of more than one other lexeme.

An endocentric compound consists of a head, i.e. the categorical part that contains the basic meaning of the whole compound, and modifiers, which restrict this meaning. For example, the English compound doghouse, where house is the head and dog is the modifier, is understood as a house intended for a dog. Endocentric compounds tend to be of the same part of speech (word class) as their head, as in the case of doghouse. Such compounds were called karmadharay in the Sanskrit tradition.

Exocentric compounds do not have a head, and their meaning often cannot be transparently guessed from its constituent parts. For example, the English compound white-collar is neither a kind of collar nor a white thing. In an exocentric compound, the word class is determined lexically, disregarding the class of the constituents. For example, a must-have is not a verb but a noun.

In the Sanskrit tradition, the type of exocentric compound exemplified by white-collar is called a bahuvrihi compound. The meaning of this type of compound can be glossed as "(one) whose B is A", where B is the second element of the compound and A the first. A bahuvrihi compound is one whose nature is expressed by neither of the words: thus a white-collar person is neither white nor a collar (the collar is colour is a metaphor for socioeconomic status). Other English examples include barefoot and Blackbeard.

Composition should not be confused with derivation, where bound morphemes are added to free ones.

A special kind of composition is incorporation, of which noun incorporation into a verbal root (as in English backstabbing, breastfeed, etc.) is most prevalent (see below).

While the notion of compound has been very important, clear definitions that work even within one language (much less across languages) have not been articulated. The study of compounds in English, for example, often includes expressions that are written as two words. This lack of precision and agreement has hampered the cross-linguistic study of compounds and even a good study within English.