In linguistics, a compound is a lexeme (less precisely, a word) that consists of more than one stem. Compounding, composition or nominal composition is the process of word formation that creates compound lexemes. That is, in familiar terms, compounding occurs when two or more words are joined to make one longer word. The meaning of the compound may be similar to or different from the meanings of its components in isolation. The component stems of a compound may be of the same part of speech--as in the case of the English word footpath, composed of the two nouns foot and path--or they may belong to different parts of speech, as in the case of the English word blackbird, composed of the adjective black and the noun bird. With very few exceptions, English compound words are stressed on their first component stem.
The process occurs readily in other Germanic languages for different reasons. Words can be concatenated both to mean the same as the sum of two words (e.g. Pressekonferenz--German for press conference) or where an adjective and noun are compounded (e.g. hvidvinsglas--Danish for white wine glass).
Compound formation rules vary widely across language types.
In a synthetic language, the relationship between the elements of a compound may be marked with a case or other morpheme. For example, the German compound Kapitänspatent consists of the lexemes Kapitän (sea captain) and Patent (license) joined by an -s- (originally a genitive case suffix); and similarly, the Latin lexeme paterfamilias contains the archaic genitive form familias of the lexeme familia (family). Conversely, in the Hebrew language compound, the word bet sefer (school), it is the head that is modified: the compound literally means "house-of book", with bayit (house) having entered the construct state to become bet (house-of). This latter pattern is common throughout the Semitic languages, though in some it is combined with an explicit genitive case, so that both parts of the compound are marked (e.g. Arabic ? ?abdu ?al-l?hi "servant-of-God").
Agglutinative languages tend to create very long words with derivational morphemes. Compounds may or may not require the use of derivational morphemes also. The longest compounds in the world may be found in the Finnic and Germanic languages. In German, extremely extendable compound words can be found in the language of chemical compounds, where, in the cases of biochemistry and polymers, they can be practically unlimited in length, mostly because the German rule suggests combining all noun adjuncts with the noun as the very last stem. German examples include Farbfernsehgerät (color television set), Funkfernbedienung (radio remote control), and the jocular word Donaudampfschifffahrtsgesellschaftskapitänsmütze (Danube steamboat shipping company Captain's hat).
In Finnish, although there is theoretically no limit to the length of compound words, words consisting of more than three components are rare. Even those with less than three components can look mysterious to non-Finnish such as hätäuloskäytävä (emergency exit). Internet folklore sometimes suggests that lentokonesuihkuturbiinimoottoriapumekaanikkoaliupseerioppilas (Airplane jet turbine engine auxiliary mechanic non-commissioned officer student) is the longest word in Finnish, but evidence of it actually being used is scant and anecdotal at best.
Compounds can be rather long when translating technical documents from English to some other language, since the lengths of the words are theoretically unlimited, especially in chemical terminology. For example, when translating an English technical document to Swedish, the term "Motion estimation search range settings" can be directly translated to rörelseuppskattningssökintervallsinställningar, though in reality, the word would most likely be divided in two: sökintervallsinställningar för rörelseuppskattning - "search range settings for motion estimation".
A common semantic classification of compounds yields four types:
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 tatpuru?a in the Sanskrit tradition.)
An exocentric compound (called a bahuvrihi compound in the Sanskrit tradition) is a hyponym of some unexpressed semantic category (such as a person, plant, or animal): none (neither) of its components can be perceived as a formal head, and its 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. 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's colour is a metonym for socioeconomic status). Other English examples include barefoot.
Copulative compounds are compounds with two semantic heads.
Appositional compounds are lexemes that have two (contrary) attributes that classify the compound.
|endocentric||A+B denotes a special kind of B||darkroom, smalltalk|
|exocentric||A+B denotes a special kind of an unexpressed semantic head||skinhead, paleface (head: 'person')|
|copulative||A+B denotes 'the sum' of what A and B denote||bittersweet, sleepwalk|
|appositional||A and B provide different descriptions for the same referent||actor-director, maidservant|
Most natural languages have compound nouns. The positioning of the words (i.e. the most common order of constituents in phrases where nouns are modified by adjectives, by possessors, by other nouns, etc.) varies according to the language. While Germanic languages, for example, are left-branching when it comes to noun phrases (the modifiers come before the head), the Romance languages are usually right-branching.
In French, compound nouns are often formed by left-hand heads with prepositional components inserted before the modifier, as in chemin-de-fer 'railway', lit. 'road of iron', and moulin à vent 'windmill', lit. 'mill (that works)-by-means-of wind'.
In Turkish, one way of forming compound nouns is as follows: yelde?irmeni 'windmill' (yel: wind, de?irmen-i: mill-possessive); demiryolu 'railway' (demir: iron, yol-u: road-possessive).
A type of compound that is fairly common in the Indo-European languages is formed of a verb and its object, and in effect transforms a simple verbal clause into a noun.
In Spanish, for example, such compounds consist of a verb conjugated for the second person singular imperative followed by a noun (singular or plural): e.g., rascacielos (modelled on "skyscraper", lit. 'scratch skies'), sacacorchos ('corkscrew', lit. 'pull corks'), guardarropa ('wardrobe', lit. 'store clothes'). These compounds are formally invariable in the plural (but in many cases they have been reanalyzed as plural forms, and a singular form has appeared). French and Italian have these same compounds with the noun in the singular form: Italian grattacielo, 'skyscraper'; French grille-pain, 'toaster' (lit. 'toast bread').
This construction exists in English, generally with the verb and noun both in uninflected form: examples are spoilsport, killjoy, breakfast, cutthroat, pickpocket, dreadnought, and know-nothing.
Also common in English is another type of verb-noun (or noun-verb) compound, in which an argument of the verb is incorporated into the verb, which is then usually turned into a gerund, such as breastfeeding, finger-pointing, etc. The noun is often an instrumental complement. From these gerunds new verbs can be made: (a mother) breastfeeds (a child) and from them new compounds mother-child breastfeeding, etc.
In the Australian Aboriginal language Jingulu, a Pama-Nyungan language, it is claimed that all verbs are V+N compounds, such as "do a sleep", or "run a dive", and the language has only three basic verbs: do, make, and run.
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).
Verb-verb compounds are sequences of more than one verb acting together to determine clause structure. They have two types:
Serial verb expressions in English may include What did you go and do that for?, or He just upped and left; this is however not quite a true compound since they are connected by a conjunction and the second missing arguments may be taken as a case of ellipsis.
Compound prepositions formed by prepositions and nouns are common in English and the Romance languages (consider English on top of, Spanish encima de, etc.). Hindi has a small number of simple (i.e., one-word) postpositions and a large number of compound postpositions, mostly consisting of simple postposition ke followed by a specific postposition (e.g., ke pas, "near"; ke n?che, "underneath").
Tamil: In Cemmozhi (Classical Tamil), rules for compounding are laid down in grammars such as Tolkappiyam and Nann?l, in various forms, under the name punarcci. Examples of compounds include kopuram from 'k?' (king) + 'puram' (exterior). Sometimes phonemes may be inserted during the blending process such as in kovil from 'k?' (king) + 'il' (home). Other types are like vennai (butter) from 'veai' (white) + 'nei' (ghee); note how 'veai' becomes 'ven'.
In ko?untamizh (Non-standard Tamil), parts of words from other languages may be morphed into Tamil. Common examples include 'ratta-azhuttam' (blood pressure) from the Sanskrit rakta (blood) and Cemmozhi 'azhuttam' (pressure); note how rakta becomes ratta in Tamil order to remove the consonant-cluster. This also happens with English, for examples k?pi-ka?ai (coffee shop) is from English coffee, which becomes k?pi in Tamil, and the Tamil ka?ai meaning shop.
In Germanic languages, compounds are formed by prepending a descriptive word in front of the main word. For example, "starfish" is a specific "fish" with a "star" shape. Likewise, the noun phrase "star shape" means a star-like shape. While some compounds (like "starfish") may have a predefined meaning, compounds like "star shape" and "starlike" can be composed when needed, and their interpretations are bound by the rules of compounding. Germanic compounds inherit the lexical category of the main word, and are inflected by inflecting the main word. That is to say, since "fish" and "shape" are nouns, "starfish" and "star shape" must also be nouns, and take plural forms "starfishes" and "star shapes". This principle still holds for languages that express definiteness by inflection (as in North Germanic), whereas for languages that use a definite article instead, the definite article precedes the whole compound rather than intermingling with it. The compound is understood as a word in its own right. As such, it may in turn be used in new compounds, so forming an arbitrarily long word is trivial. This contrasts to Romance languages, where prepositions are more used to specify word relationships instead of concatenating the words.
As a member of the Germanic family of languages, English is special in that compounds, as a main rule, are written in their separate parts. As in Dutch or German, noun phrases like "Girl Scout troop", "city council member", and "cellar door" are arguably compound nouns and used as such in speech. Writing them as separate words or together is merely an orthographic convention.
In the Russian language compounding is a common type of word formation, and several types of compounds exist, both in terms of compounded parts of speech and of the way of the formation of a compound.
Compound nouns may be agglutinative compounds, hyphenated compounds (?- 'folding table' lit. 'table-book', i.e., "book-like table"), or abbreviated compounds (acronyms: 'kolkhoz'). Some compounds look like acronym, while in fact they are an agglutinations of type stem + word 'Akademgorodok' (from akademichesky gorodok 'academic village'). In agglutinative compound nouns, an agglutinating infix is typically used 'steamship': + ? + . Compound nouns may be created as noun+noun, adjective + noun, noun + adjective (rare), noun + verb (or, rather, noun + verbal noun).
Compound adjectives may be formed either per se, e.g., ?-? 'white-pink', or as a result of compounding during the derivation of an adjective from a multi-word term? ([k?mnn'strovskj pr?'spkt]) 'Stone Island Avenue', a street in St.Petersburg.
Reduplication in Russian language is also a source of compounds.
Sanskrit is very rich in compound formation with seven major compound types and as many as 55 sub-types. The compound formation process is productive, so it is not possible to list all Sanskrit compounds in a dictionary. Compounds of two or three words are more frequent, but longer compounds with some running through pages are not rare in Sanskrit literature. Some examples are below (hyphens below show individual word boundaries for ease of reading but are not required in original Sanskrit).
Although there is no universally agreed-upon guideline regarding the use of compound words in the English language, in recent decades written English has displayed a noticeable trend towards increased use of compounds. Recently, many words have been made by taking syllables of words and compounding them, such as pixel (picture element) and bit (binary digit). This is called a syllabic abbreviation.
In Dutch and the Scandinavian languages there is an unofficial trend toward splitting compound words, known in Norwegian as særskriving, in Swedish as särskrivning (literally "separate writing"), and in Dutch as Engelse ziekte (the "English disease"). Because the Scandinavian languages rely heavily on the distinction between the compound word and the sequence of the separate words it consists of, this has serious implications. For example, the adjective røykfritt (literally "smokefree", meaning no smoking allowed) if separated into its composite parts, would mean røyk fritt ("smoke freely"). In Dutch, compounds written with spaces may also be confused, but can also be interpreted as a sequence of a noun and a genitive (which is unmarked in Dutch) in formal abbreviated writing. This may lead to, for example, commissie vergadering ("commission meeting") being read as "commission of the meeting" rather than "meeting of the commission" (normally spelled commissievergadering).
The German spelling reform of 1996 introduced the option of hyphenating compound nouns when it enhances comprehensibility and readability. This is done mostly with very long compound words by separating them into two or more smaller compounds, like Eisenbahn-Unterführung (railway underpass) or Kraftfahrzeugs-Betriebsanleitung (car manual). Such practice is also permitted in other Germanic languages, e.g. Danish and Norwegian (Bokmål and Nynorsk alike), and is even encouraged between parts of the word that have very different pronunciation, such as when one part is a loan word or an acronym.