Types of compound nouns

Analyzability (transparency)

In general, the meaning of a compound noun is a specialization of the meaning of its head. The modifier limits the meaning of the head. This is most obvious in descriptive compounds (known as karmadharaya compounds in the Sanskrit tradition), in which the modifier is used in an attributive or appositional manner. A blackboard is a particular kind of board, which is (generally) black, for instance.

In determinative compounds, however, the relationship is not attributive. For example, a footstool is not a particular type of stool that is like a foot. Rather, it is a stool for one's foot or feet. (It can be used for sitting on, but that is not its primary purpose.) In a similar manner, an office manager is the manager of an office, an armchair is a chair with arms, and a raincoat is a coat against the rain. These relationships, which are expressed by prepositions in English, would be expressed by grammatical case in other languages. (Compounds of this type are known as tatpurusha in the Sanskrit tradition.)

Both of the above types of compounds are called endocentric compounds because the semantic head is contained within the compound itself—a blackboard is a type of board, for example, and a footstool is a type of stool.

However, in another common type of compound, the exocentric (known as a bahuvrihi compound in the Sanskrit tradition), the semantic head is not explicitly expressed. A redhead, for example, is not a kind of head, but is a person with red hair. Similarly, a blockhead is also not a head, but a person with a head that is as hard and unreceptive as a block (i.e. stupid). And a lionheart is not a type of heart, but a person with a heart like a lion (in its bravery, courage, fearlessness, etc.).

There is a general way to tell the two apart. In a compound "[X . Y]":

• Can one substitute Y with a noun that is a Y, or a verb that does Y? This is an endocentric compound.
• Can one substitute Y with a noun that is with Y? This is an exocentric compound.

Exocentric compounds occur more often in adjectives than nouns. A V-8 car is a car with a V-8 engine rather than a car that is a V-8, and a twenty-five-dollar car is a car with a worth of $25, not a car that is $25. The compounds shown here are bare, but more commonly, a suffixal morpheme is added, such as -ed: a two-legged person is a person with two legs, and this is exocentric.

On the other hand, endocentric adjectives are also frequently formed, using the suffixal morphemes -ing or -er/or. A people-carrier is a clear endocentric determinative compound: it is a thing that is a carrier of people. The related adjective, car-carrying, is also endocentric: it refers to an object which is a carrying-thing (or equivalently, which does carry).

These types account for most compound nouns, but there are other, rarer types as well. Coordinative, copulative or dvandva compounds combine elements with a similar meaning, and the compound meaning may be a generalization instead of a specialization. Bosnia-Herzegovina, for example, is the combined area of Bosnia and Herzegovina, but a fighter-bomber is an aircraft that is both a fighter and a bomber. Iterative or amredita compounds repeat a single element, to express repetition or as an emphasis. Day by day and go-go are examples of this type of compound, which has more than one head.

Analyzability may be further limited by cranberry morphemes and semantic changes. For instance, the word butterfly, commonly thought to be a metathesis for flutter by, which the bugs do, is actually based on an old wives' tale that butterflies are small witches that steal butter from window sills. Cranberry is a part translation from Low German, which is why we cannot recognize the element cran (from the Low German kraan or kroon, "crane"). The ladybird or ladybug was named after the Christian expression "our Lady, the Virgin Mary".

In the case of verb+noun compounds, the noun may be either the subject or the object of the verb. In playboy, for example, the noun is the subject of the verb (the boy plays), whereas it is the object in callgirl (someone calls the girl).

Sound patterns

Stress patterns may distinguish a compound word from a noun phrase consisting of the same component words. For example, a black board, adjective plus noun, is any board that is black, and has equal stress on both elements.^{[lower-alpha 2]} The compound blackboard, on the other hand, though it may have started out historically as black board, now is stressed on only the first element, black.^{[lower-alpha 3]} Thus a compound such as the White House normally has a falling intonation which a phrase such as a white house does not.^{[lower-alpha 4]}

Solid compound modifiers

There are some well-established permanent compound modifiers that have become solid over a longer period, especially in American usage: earsplitting, eyecatching, and downtown.

However, in British usage, these, apart from downtown, are more likely written with a hyphen: ear-splitting, eye-catching.

Other solid compound modifiers are for example:

• Numbers that are spelled out and have the suffix -fold added: "fifteenfold", "sixfold".
• Points of the compass: northwest, northwestern, northwesterly, northwestwards. In British usage, the hyphenated and open versions are more common: north-western, north-westerly, north west, north-westwards.

Hyphenated compound modifiers

Major style guides advise consulting a dictionary to determine whether a compound modifier should be hyphenated; the dictionary's hyphenation should be followed even when the compound modifier follows a noun (that is, regardless of whether in attributive or predicative position), because they are permanent compounds^[6][7] (whereas the general rule with temporary compounds is that hyphens are omitted in the predicative position because they are used only when necessary to prevent misreading, which is usually only in the attributive position, and even there, only on a case-by-case basis).^[8][9]

Generally, a compound modifier is hyphenated if the hyphen helps the reader differentiate a compound modifier from two adjacent modifiers that modify the noun independently. Compare the following examples:

• "small appliance industry": a small industry producing appliances
• "small-appliance industry": an industry producing small appliances^{[lower-alpha 5]}

The hyphen is unneeded when capitalization or italicization makes grouping clear:

• "old English scholar": an old person who is English and a scholar, or an old scholar who studies English
• "Old English scholar": a scholar of Old English.
• "De facto proceedings" (not "de-facto")

If, however, there is no risk of ambiguities, it may be written without a hyphen: Sunday morning walk (a "walk on Sunday morning" is practically the same as a "morning walk on Sunday").

Hyphenated compound modifiers may have been formed originally by an adjective preceding a noun, when this phrase in turn precedes another noun:

• "Round table" → "round-table discussion"
• "Blue sky" → "blue-sky law"
• "Red light" → "red-light district"
• "Four wheels" → "four-wheel drive" (historically, the singular or root is used, not the plural)

Others may have originated with a verb preceding an adjective or adverb:

• "Feel good" → "feel-good factor"
• "Buy now, pay later" → "buy-now pay-later purchase"

Yet others are created with an original verb preceding a preposition.

• "Stick on" → "stick-on label"
• "Walk on" → "walk-on part"
• "Stand by" → "stand-by fare"
• "Roll on, roll off" → "roll-on roll-off ferry"

The following compound modifiers are always hyphenated when they are not written as one word:

• An adjective preceding a noun to which -d or -ed has been added as a past-participle construction, used before a noun:
  • "loud-mouthed hooligan"
  • "middle-aged lady"
  • "rose-tinted glasses"
• A noun, adjective, or adverb preceding a present participle:
  • "an awe-inspiring personality"
  • "a long-lasting affair"
  • "a far-reaching decision"
• Numbers, whether or not spelled out, that precede a noun:^{[lower-alpha 5]}
  • "seven-year itch"
  • "five-sided polygon"
  • "20th-century poem"
  • "30-piece band"
  • "tenth-storey window"
  • "a 20-year-old man" (as a compound modifier) and "the 20-year-old" (as a compound noun)—but "a man, who is 20 years old"
• A numeral with the affix -fold has a hyphen (15-fold), but when spelled out takes a solid construction (fifteenfold).
• Numbers, spelled out or not, with added -odd: sixteen-odd, 70-odd.
• Compound modifiers with high- or low-: "high-level discussion", "low-price markup".
• Colours in compounds:
  • "a dark-blue sweater"
  • "a reddish-orange dress".
• Fractions as modifiers are hyphenated: "two-thirds majority", but if numerator or denominator are already hyphenated, the fraction itself does not take a hyphen: "a thirty-three thousandth part". (Fractions used as nouns have no hyphens: "I ate two thirds of the pie.")
• Comparatives and superlatives in compound adjectives also take hyphens:
  • "the highest-placed competitor"
  • "a shorter-term loan"
• However, a construction with most is not hyphenated:
  • "the most respected member".
• Compounds including two geographical modifiers:

• "Anglo-Indian"

But not

• "Central American", which refers to people from a specific geographical region
• "African American", as a hyphen is seen to disparage minority populations as a hyphenated ethnicity^[10]

The following compound modifiers are not normally hyphenated:

• Compound modifiers that are not hyphenated in the relevant dictionary^[6][7][9] or that are unambiguous without a hyphen.^[8]
• Where there is no risk of ambiguity:
  • "a Sunday morning walk"
• Left-hand components of a compound modifier that end in -ly and that modify right-hand components that are past participles (ending in -ed):
  • "a hotly disputed subject"
  • "a greatly improved scheme"
  • "a distantly related celebrity"
• Compound modifiers that include comparatives and superlatives with more, most, less or least:
  • "a more recent development"
  • "the most respected member"
  • "a less opportune moment"
  • "the least expected event"
• Ordinarily hyphenated compounds with intensive adverbs in front of adjectives:
  • "very much admired classicist"
  • "really well accepted proposal"

Hyphenation

Compound verbs with single-syllable modifiers are often solid, or unhyphenated. Those with longer modifiers may originally be hyphenated, but as they became established, they became solid, e.g.

• overhang (English origin)
• counterattack (Latin origin)

There was a tendency in the 18th century to use hyphens excessively, that is, to hyphenate all previously established solid compound verbs. American English, however, has diminished the use of hyphens, while British English is more conservative.

Phrasal verbs

English syntax distinguishes between phrasal verbs and adverbial adjuncts. Consider the following sentences:

I held up my hand implies that I raised my hand.

I held up the negotiations implies that I delayed the negotiations.

I held up the bank to the highest standard implies that I demanded model behavior regarding the bank.

I held up the bank implies either (a) that I robbed the bank or (b) that I lifted upward a bank [either literally, as for a toy bank, or figuratively, as in putting a bank forward as an example of something (although usually then the sentence would end with ... as an exemplar. or similar)].

Each of the foregoing sentences implies a contextually distinguishable meaning of the word, "up," but the fourth sentence may differ syntactically, depending on whether it intends meaning (a) or (b). Specifically, the first three sentences render held up as a phrasal verb that expresses an idiomatic, figurative, or metaphorical sense that depends on the contextual meaning of the particle, "up." The fourth sentence, however, ambiguously renders up either as (a) a particle that complements "held," or as (b) an adverb that modifies "held." The ambiguity is minimized by rewording and providing more context to the sentences under discussion:

I held my hand up implies that I raised my hand.

I held the negotiations up implies that I delayed the negotiations.

I held the bank up to the highest standard implies that I expect model behavior regarding the bank.

I held the bank up upstairs implies that I robbed the upstairs bank.

I held the bank up the stairs implies that I lifted a (toy) bank along an upstairs route.

Thus, the fifth sentence renders "up" as the head word of an adverbial prepositional phrase that modifies, the verb, held. The first four sentences remain phrasal verbs.

The Oxford English Grammar (ISBN 0-19-861250-8) distinguishes seven types of phrasal verbs in English:

• intransitive phrasal verbs (e.g. give in)
• transitive phrasal verbs (e.g. find out [discover])
• monotransitive prepositional verbs (e.g. look after [care for])
• doubly transitive prepositional verbs (e.g. blame [something] on [someone])
• copular prepositional verbs. (e.g. serve as)
• monotransitive phrasal-prepositional verbs (e.g. look up to [respect])
• doubly transitive phrasal-prepositional verbs (e.g. put [something] down to [someone] [attribute to])

English has a number of other kinds of compound verb idioms. There are compound verbs with two verbs (e.g. make do). These too can take idiomatic prepositions (e.g. get rid of). There are also idiomatic combinations of verb and adjective (e.g. come true, run amok) and verb and adverb (make sure), verb and fixed noun (e.g. go ape); and these, too, may have fixed idiomatic prepositions (e.g. take place on).

Misuses of the term

"Compound verb" is often confused with:

1. "verb phrase"/"verbal phrase"—Headed by a verb, many verbal phrases are multi-word but some are one-word: a verb (which could be a compound verb).
2. "phrasal verb"—A sub-type of verb phrase, which has a Grammatical particle before or after the verb, often having a more or less idiomatic meaning.
3. "complex verb"—A type of complex phrase: In linguistics, while both "compound" and "complex" contrast with "simple", they are not synonymous (simple involves a single element, compound involves multiple similar elements, complex involves multiple dissimilar elements).