A compound term is a combination of two or more words that, to varying degrees, have become unified in form and meaning through frequent use together. In many cases only one syllable in the compound is stressed. The trend over the years has been for the English compound to begin as two separate words, then be hyphenated and finally, if there is no structural impediment to union, become a single word written without a space or hyphen. Whatever its form, the compound frequently serves to avoid circumlocution and create a more concise style.
The existence of three different forms for compounds leads to considerable instability and variation in their presentation, and hyphenation has become one of the most controversial points of editorial style. Dictionaries vary widely in the forms they choose for specific compounds: "hot-line" in the Gage Canadian Dictionary, "hot line" in the Canadian Dictionary of the English Language and "hotline" in The Concise Oxford Dictionary, for example.
All authorities agree that the matter of hyphenation is one where the exercise of individual judgment is required, and the rules that follow are not intended to preclude its use. Where various authorities disagree, it has been thought desirable to err on the side of caution and recommend use of the hyphen for the sake of clarity.
Bear in mind the distinction between a compound term used before a noun (attributively) and one in some other position (predicatively). As a general rule, terms that take a hyphen when preceding a noun do not take one in other positions, but there are enough exceptions to warrant their being noted, and this is done below.
Although they do not form true compounds, prefixes and suffixes are treated in this chapter because they pose similar problems with respect to hyphenation.
Consult the Gage Canadian Dictionary for the form of frequently used compounds (including those based on prefixes and suffixes), and then follow the rules below for those not found in Gage.
For information on hyphens with place names in French, see Chapter 15 Geographical Names.
(a) Hyphenate two nouns representing different but equally important functions, i.e. where the hyphen denotes the relationship "both A and B":
(b) Hyphenate nouns normally written as two words, when they have a modifier and when ambiguity would otherwise result:
Similarly, compound nouns normally written as a single word must be separated into their component parts and then joined to their modifier by a hyphen when the modifier applies only to the first component:
(c) Hyphenate compound units of measurement made by combining single units that stand in a mathematical relationship to each other:
(d) Hyphenate compounds that include a finite verb:
(e) Hyphenate nouns of family relationship formed with great and in-law:
(a) Hyphenate noun-plus-adjective compounds (in that order), whether used attributively or predicatively:
(b) Hyphenate noun-plus-participle compounds regardless of the position:
There are a number of them, including handmade and handwritten.
(c) Do not hyphenate noun-plus-gerund compounds (present participle used as a noun); they may be written as one or as separate words:
See 2.04 Compound adjectives; adjectives and participles in compounds(e) for such compounds used adjectivally.
(a) Hyphenate adjective-plus-noun and participle-plus-noun compounds modifying another noun, when ambiguity might otherwise result:
When the compound is used predicatively, retain the hyphen only when the expression remains adjectival:
(b) Hyphenate compound adjectives made up of two adjectives that describe a colour without the suffix ish, whether they are placed before or after the noun. Hyphenate compounds with the suffix only when they precede the noun:
Do not hyphenate adjectives indicating a specific shade (even if they precede the noun):
(c) Hyphenate adjective-plus-participle compounds, whether used before the noun or after it:
(d) Hyphenate compounds made up of an adjective plus a noun to which the ending ed has been added, in any position in the sentence:
(e) Hyphenate two-word compound adjectives consisting of a noun plus a gerund when they precede the noun:
See also 2.03 Nouns with adjectives and participles(c).
(f) Hyphenate compound adjectives whose final constituent is an adverb of direction or place (in, out, down, up, etc.) when they precede the noun:
(g) Hyphenate compound adjectives made up of a preposition and a noun:
(h) Hyphenate a compound adjective one of whose constituents is a finite verb:
(i) Hyphenate phrases of more than two words, at least one of which is an adverb or preposition, used as attributive adjectives:
(j) Do not hyphenate French or foreign words used as adjectives or in italics, proper nouns used as adjectives, or words in quotation marks:
Note that this rule does not apply to French or foreign words no longer considered as such:
(k) Do not hyphenate chemical terms used as adjectives:
(l) Hyphenate compound proper adjectives that form a true compound, but do not hyphenate those in which a proper adjective is combined with a simple modifier:
(a) Compound verbs may be either hyphenated or written solid. The only safe rule is to check your dictionary:
(b) If the infinitive form of the verb (e.g. to air-condition) is hyphenated, retain the hyphen in all other forms, except as illustrated in (c):
(c) Hyphenate gerunds formed from hyphenated compound verbs only if they are followed by a noun object:
(a) Adverb-plus-participle compounds are among the most troublesome. Do not hyphenate those in which the adverb ends in ly:
In other cases, hyphenate before the noun:
Do not hyphenate when the compound follows the noun or pronoun and contains a past participle:
When the compound follows the noun or pronoun and contains a present participle, do not hyphenate if the participle has a verbal function, but hyphenate if it is adjectival in nature:
(b) Do not hyphenate compounds consisting of an adverb or adverbial phrase plus an adjective (in that order) unless there is a danger of misreading:
(a) Hyphenate a prefix joined to a proper noun or adjective:
transatlantic and transpacific.
(b) Hyphenate expressions beginning with the prefixes ex (when it means "former"), self and all, when used to form adjectives or nouns, and those beginning with quasi when used to form adjectives:
However, when self is the base word to which a suffix is added, do not hyphenate:
(c) Most words beginning with the following prefixes are written as one word: after, ante, anti, bi, co, counter, de, down, extra, infra, inter, intra, iso, macro, micro, multi, over, photo, poly, post, pre, pro, pseudo, re, retro, semi, stereo, sub, super, trans, tri, ultra, un, under and up:
However, there are many exceptions. Check the Gage Canadian Dictionary when in doubt, and see below and 2.07 Prefixes(a) for specific types of exception.
Use a hyphen when the word following the prefix begins with the same vowel as the one with which the prefix ends and when the compound’s appearance would be confusing without the hyphen:
In certain cases, use the hyphen to preserve a difference in meaning between the hyphenated and the solid compound:
(d) Write SI/metric unit compounds as one word:
(e) Hyphenate chemical terms preceded by an italicized prefix:
The words any, every, no and some form solid compounds when combined with body, thing and where:
However, when one is the second element, write no as a separate, unhyphenated word in all situations and write any and every as separate, unhyphenated words if one is followed by a prepositional phrase beginning with of:
Write the following compounds as one word, except where this would result in a double l and where the compound is a temporary one coined for a specific purpose or text:
Since usage depends on the degree of familiarity of the compound, no general rule can be stated. Note the following:
(c) Hyphenate compounds made up of a numerical expression plus odd or strong:
(d) Write compounds with fold and score as one word, except when the numerical expression itself already has a hyphen:
(a) Hyphenate compound cardinal and ordinal numerals from twenty-one (twenty-first) to ninety-nine (ninety-ninth) when written out:
(b) Hyphenate a compound adjective in which one element is a cardinal or ordinal numeral and the other a noun:
Do not hyphenate before a symbol that is not a letter, and do not hyphenate a modifier in which the numeral, written in full, is itself a compound:
In cases such as the second example, use the abbreviated form (a 250-ha farm) if at all possible.
See 5.05 Adjectival expressions and juxtaposed numbers for further information.
(c) Do not hyphenate a possessive noun preceded by a numerical expression:
(d) Hyphenate expressions of time of day as follows when writing out numerals:
Hyphenate fractions used as modifiers and written in full, unless the numerator or denominator already contains a hyphen:
one and a half months
Usage is divided on whether fractions used as nouns should be hyphenated. We recommend that the hyphen not be used in such cases:
Hyphenate as follows when an element common to successive compound adjectives is omitted:
Write as one word compass directions consisting of two points, but use a hyphen after the first point in those compounds consisting of three points:
Hyphenate compounds with the endings elect and designate:
Hyphenate most titles beginning with the prefix vice or with then and the names of certain military and administrative positions in which a noun is followed by another noun, an adjective or a prepositional phrase:
There are, however, many common exceptions to this rule, e.g.:
Note that in Canadian usage the hyphen is used in compounds designating military ranks such as Lieutenant-General, Vice-Admiral and Rear-Admiral, whereas the American practice is to omit the hyphen. Similarly, the official title of the second-highest-ranking official of the United States is Vice President.
Hyphenate numerals or single letters and the words they modify:
Do not hyphenate a compound adjective when the second element is a letter or figure:
(a) In forming the plurals of compound terms, pluralize the significant word. If both words are of equal significance, pluralize both. Pluralize the last one if no one word is significant in itself:
(b) When a noun is hyphenated with a preposition, the plural is formed on the noun:
(c) When neither word of a compound is a noun, the plural is formed on the last word:
(d) Add s to nouns ending in ful:
In order to ensure clear, unambiguous presentation, avoid dividing words at the end of a line as much as possible. If word division is necessary, text comprehension and readability should be your guides. The accepted practice is summarized below:1
(a) Usually, words may be divided between syllables (the Gage Canadian Dictionary shows syllabication clearly for all its entries), but not all syllable breaks are acceptable as end-of-line breaks, as rules (b) to (m) explain.
(b) Two-letter syllables should not be carried over to the next line (fully, not ful-ly; stricken, not strick-en). Similarly, final syllables in which a liquid l is the only pronounced vowel sound should not be carried over (pos-sible, not possi-ble; prin-ciples, not princi-ples).
(c) Do not divide words of one syllable or words in which the second "syllable" contains only a silent e (aimed, helped, vexed, etc.).
(d) One-letter word divisions are not permissible. Do not divide words such as again, item, enough and even.
(e) Avoid awkward divisions that would result from attempting to divide words such as every, only, eighteen and people.
(f) Divide between a prefix and a following letter (pre-fix, re-location).
(g) Divide a word between the root and the suffix (care-less, convert-ible, world-wide).
(h) When a consonant is doubled, divide it for purposes of word division (equip-ping, rub-ber).
(i) Avoid misleading breaks that might cause the reader to confuse one word with another, as in read-just and reap-pear. Similarly, such words as women and often should be left unbroken.
(j) Divide compounds only at the hyphen, if possible (court-martial, not court-mar-tial). A compound written as one word should be divided between its elements (hot-house, sail-boat).
(k) Most words ending in ing may be divided at that syllable. When the final consonant is doubled before ing, however, the second consonant is carried over (bid-ding, control-ling). When the verb has an l preceded by a consonant, carry over the letter preceding the l (han-dling, dwin-dling, tin-kling).
(l) Do not divide abbreviations, contractions and numbers (UNDP, won’t, 235 006 114.37). Abbreviations or symbols used with numerals should not be separated from the numerals (16 kg, 0 °C, s. 4, 11:55 a.m.).
(m) Do not divide the last word on a page.
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