In linguistics, a compound is a lexeme (less precisely, a word or sign) that consists of more than one stem. Compounding, composition or nominal composition is the process of word formation that creates compound lexemes. Compounding occurs when two or more words or signs are joined to make a longer word or sign. Consequently, a compound is a unit composed of more than one stem, forming words or signs. If the joining of the words or signs is orthographically represented with a hyphen, the result is a hyphenated compound (e.g., must-have, hunter-gatherer). If they are joined without an intervening space, it is a closed compound or solid compound (e.g., footpath, blackbird). If they are joined with a space (e.g. school bus, cell phone, high school, lowest common denominator), then the result – at least in English – is an open compound.
The meaning of the compound may be similar to or different from the meaning 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.
Some languages easily form compounds from what in other languages would be a multi-word expression. This can result in unusually long words, a phenomenon known in German (which is one such language) as ("tapeworm words").
Compounding extends to Sign languages as well, where compounds are also created by combining two or more sign stems.
So-called "classical compounds" are compounds derived from classical Latin or ancient Greek roots.
In many languages, including English, Spanish, Latin and German, all numbers greater than twenty that have more than one non-zero digit are written and spoken as compounds.
Formation of compounds 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 consists of the lexemes (sea captain) and (license) joined by an -s- (originally a genitive case suffix); and similarly, the Latin lexeme contains the archaic genitive form of the lexeme (family); in the English word daisy, the saxon genitive (equivalent to -'s) was etymologically fossilized from the Old English compound dæġes ēage (literally, "day's eye"). Conversely, in the Hebrew language compound, the word בֵּית סֵפֶר (school), it is the head that is modified: the compound literally means "house-of book", with בַּיִת (house) having entered the construct state to become בֵּית (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.
Agglutinative languages tend to create very long words with derivational morphemes. Compounds may or may not require the use of derivational morphemes also.
In German, extremely extendable compound words can be found in many different domains. In the language of chemistry, for example, compounds can be practically unlimited in length, mostly because the German rule suggests combining all noun adjuncts with the noun as the last stem. German examples include (color television set), (radio remote control), and the often quoted jocular word (originally only two Fs, Danube-Steamboat-Shipping Company captain['s] hat), which can of course be made even longer and even more absurd, e.g. Donaudampfschifffahrtsgesellschaftskapitänsmützenreinigungsausschreibungsverordnungsdiskussionsanfang ("beginning of the discussion of a regulation on tendering of Danube steamboat shipping company captain hats") etc. According to several editions of the Guinness Book of World Records, the longest published German word has 79 letters and is Donaudampfschiffahrtselektrizitätenhauptbetriebswerkbauunterbeamtengesellschaft ("Association for Subordinate Officials of the Main Electric[ity] Maintenance Building of the Danube Steam Shipping"), but there is no evidence that this association ever actually existed.
In Finnish, although there is theoretically no limit to the length of compound words, words consisting of more than three components are rare. Internet folklore sometimes suggests that (airplane jet turbine engine auxiliary mechanic non-commissioned officer student) is the longest word in Finnish, but evidence of its actual use 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 , though in reality, the word would most likely be divided in two: – "search range settings for motion estimation".
Subclasses
Semantic classification
A common semantic classification of compounds yields four types:
endocentric exocentric copulative appositional
An endocentric compound (tatpuruṣa in the Sanskrit tradition) consists of a head, i.e. the categorical part that contains the basic meaning of the whole compound, and modifiers, which restrict this meaning. The compound word is a hyponym of the head. 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.
An exocentric compound (bahuvrihi in the Sanskrit tradition) is a compound where the semantic category (e.g. person, plant, or animal) is not stated. Neither of its components is a 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. Other English examples include barefoot.
Copulative compounds (dvandva in the Sanskrit tradition) are compounds with two semantic heads. These are commonly used to describe points on a gradual scale, such as yellow-green.
Appositional compounds are lexemes that have two (contrary or simultaneous) attributes that classify the compound.
Type Description Examples endocentric A+B denotes a special kind of Bdarkroom, smalltalk exocentric A+B denotes a special kind of an unexpressed different semantic meaning Credhead, scarecrow copulative A+B denotes 'the sum' of what A and B denotebittersweet, sleepwalk appositional A and B provide different descriptions for the same referenthunter-gatherer, maidservant
Syntactic classification
Noun–noun compounds All 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.
English compound nouns can be spaced, hyphenated, or solid, and they sometimes change orthographically in that direction over time, reflecting a semantic identity that evolves from a mere collocation to something stronger in its solidification. This theme has been summarized in usage guides under the aphorism that "compound nouns tend to solidify as they age"; thus a compound noun such as place name begins as spaced in most attestations and then becomes hyphenated as place-name and eventually solid as placename, or the spaced compound noun file name directly becomes solid as filename without being hyphenated. +Types of English compound nounsTypeDescriptionExamplesSpaced (or open)The words are not visibly connected in writing.place name, ice creamHyphenatedA hyphen is used to join the words.place-name, hunter-gathererSolid (or closed)When written, there is no space or intervening punctuation.placename, scarecrow German, a fellow West Germanic language, has a somewhat different orthography, whereby compound nouns are virtually always required to be solid or at least hyphenated; even the hyphenated styling is used less now than it was in centuries past.
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: yeldeğirmeni 'windmill' (yel: wind, değirmen-i: mill-possessive); demiryolu 'railway' (demir: iron, yol-u: road-possessive).
Occasionally, two synonymous nouns can form a compound noun, resulting in a pleonasm. One example is the English word pathway.
In Arabic, there are two distinct criteria unique to Arabic, or potentially Semitic languages in general. The initial criterion involves whether the possessive marker li-/la 'for/of' appears or is absent when the first element is definite. The second criterion deals with the appearance/absence of the possessive marker li-/la 'for/of' when the first element is preceded by a cardinal number.
Verb–noun compounds A type of compound that is fairly common in Indo-European languages is formed by a verb and its object. It 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.
A special kind of compounding is incorporation, of which noun incorporation into a verbal root (as in English backstabbing, breastfeed, etc.) is most prevalent. 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.R. Pensalfini, Jingulu Grammar, Dictionary and Texts, PhD thesis (MIT, 1992), 138–9.
Verb–verb compounds
Verb–verb compounds are sequences of more than one verb acting together to determine clause structure. They have two types:
In a serial verb, two actions, often sequential, are expressed in a single clause. For example:
In each case, the two verbs together determine the semantics and argument structure.