A compound modifier is a compound of two or more attributive words: that is, two or more words that collectively modify a noun. Compound modifiers are grammatically equivalent to single-word modifiers, and can be used in combination with other modifiers. The constituents of compound modifiers need not be adjectives; combinations of nouns, determiners, and other parts of speech are also common. For example, man-eating and one-way . The punctuation of compound modifiers in English depends on their grammatical role. Attributive compounds—modifiers within the noun phrase—are typically hyphenated, whereas the same compounds used as predicates will typically not be, unless they are permanent compounds attested as dictionary headwords.
Compound adjectives
Words that function as compound adjectives may modify a noun or a noun phrase. Take the English examples heavy metaldetector and heavy-metal detector. The former example contains only the bareadjectiveheavy to describe a device that is properly written as metal detector; the latter example contains the phrase heavy-metal, which is a compound noun that is ordinarily rendered as heavy metal absent an accompanying adjective. In the latter example, however, heavy-metal functions as a compound adjective that modifies the noun detector. Note that whether a word sequence such as "heavy + metal + detector" implies a compound adjective + noun or bare adjective + compound noun depends on the punctuation. For instance, heavy-metal detector and heavy metal detector can refer to quite different things: heavy-metal detector implies a device that detects heavy metals. By contrast, heavy metal detector, without the hyphen, refers to a metal detector that is heavy. is a bare adjective that modifies the compound noun metal detector. Thus, heavy metal detector is a bare adjective + compound noun sequence. A strategy to avoid conflation of compound adjective + noun versus bare adjective + compound nounsequences is to clearly distinguish the usage of an attributive adjective and a noun adjunct. Accordingly, the phrase heavy detector unequivocally employs a compound adjective to describe a weighty detector made of metal.
Hyphenation of elements in English
Conventionally, and with the support of modern writing guides, compound modifiers that appear before a noun phrase must include a hyphen between each word, subject to certain exceptions. Hyphens are used in this way to prevent confusion; without their use, a reader might interpret the words separately, rather than as a phrase. Hyphens join the relevant words into a single idea, a compound adjective. When a numeral and a noun are used in a compound modifier that precedes a noun, the numeral and the noun take the singular form.
Exceptions
Major style guides advise consulting a dictionary to determine whether a compound adjective should be hyphenated; compounds entered as dictionary headwords are permanent compounds, and for these, the dictionary's hyphenation should be followed even when the compound adjective precedes a noun. According to some guides, hyphens are unnecessary in familiar compounds used as adjectives "where no ambiguity could result", while other guides suggest using hyphens "generally" in such compounds used as adjectives before nouns.
Examples
Man-eating shark
Long-term contract
Zero-liability protection
Exceptions
It may be appropriate to distinguish between compound modifiers whose adverb has the suffix , such as quickly and badly, and those whose adverb does not, such as well. The -ly suffix on an adverb allows readers to understand its lexical category, showing that it is intended to modify the adjective that it precedes and so not requiring hyphenation. Quickly and badly are unambiguously adverbs. Other adverbs of the words in a compound modifier are nouns, it is seen as not necessary to hyphenate them, as misunderstanding is unlikely.
can compound. This is quite common for na-adjectives, which function essentially as attributive nounphrases, while it is relatively uncommon for i-adjectives, and is much less common than Japanese compound verbs. Common examples include and .
