There are some useful rules about when
to join or not join two different words into one, but they do not cover all cases
AREAS OF UNCERTAINTY ABOUT JOINING WORDS TOGETHER
Is it correct to write bath tub, or should it be the single word bathtub? Is every day a correct spelling, or everyday? Uncertainties like this are widespread in English, even among proficient users. They are made worse by the fact that in some cases both spellings are correct, but mean different things.
Are there any guidelines for resolving such uncertainties? It seems that in some cases there are and in some there are not. I wish here to indicate some of these guidelines. They are mostly based on the kinds of words in a pair.
Ordinary compounds are the area where the fewest guidelines exist. They include words like coursework, which I am in the habit of writing as a single word but my Microsoft Word spellchecker tells me should be two. As a linguist, I do not pay much attention to what computers say about language (see 68. How Computers Get Grammar Wrong), but the question of why ordinary compound words give especial problems is an interesting one. First, these words need to be defined.
It is mostly accurate to say that a compound word is just two words joined together into one. Linguists, though, like to speak of joined roots or stems rather than words, partly because a few compound-like words contain an element that cannot be a word by itself (e.g. horti- in horticulture), and partly perhaps because some words that are not considered compounds, such as fearless and ill-fitting, do still seem to comprise two words (see 106. Word-Like Suffixes and 146. Some Important Prefix Types).
Roots, it should be noted, are not the only possible word parts with meaning. There are also affixes (prefixes and suffixes). These are added on to roots but do not thereby make compounds. Examples are -less, -un-, in-, mis-, pre-, -ness, -tion, -al, -ly and -ing. Words like unhappy, pre-existing and international are thus not compounds. Compounds must include at least two roots. Further examples are swimsuit, homework and eavesdrop.
Some books suggest that separate words are likely to join together to make a compound when they are very frequently used together for a single idea. The problem is that many frequent combinations are not compounds (e.g. town hall and open air); and there is no apparent reason why compounds are spelt as one word while these other combinations are not.
The grammatical classes of the two words and the closeness of the link between them are other suggested spelling guides, but they are not reliable. The age of a combination is also often mentioned, the claim being that all compounds start out as two separate words, and gradually evolve through constant use first into hyphenated expressions (like fire-eater or speed-read), and eventually into compounds. However, some quite recent words are already compounds, such as bitmap in computing. The best guideline I can suggest for correctly spelling two closely-linked words is to check whether they are listed as a single word in a dictionary.
NOUNS DERIVED FROM PHRASAL VERBS
Happily, some compound words do have some logic about them. Most are words whose roots, if written as two words, are also correct but have different meaning and grammar, so that the meaning indicates the spelling or vice versa. A particularly large category of such words may be illustrated with the compound noun takeaway (meaning “cooked food not eaten in the place of purchase”). If its two roots are written separately as take away, they become a “phrasal” verb – a combination of a simple English verb (take) with a small adverb (away) – meaning “remove”. For further phrasal verb details and links, see 139. Phrasal Verbs.
There are many other nouns that can be made into phrasal verbs, e.g. takeover, makeup, cutoff, breakout, setdown, pickup, washout, login and stopover. In writing there is always a need to remember that, if the two “words” are going to do the job of a verb, they must be spelled separately, but if they are going to act like a noun, they must be written together.
OTHER CHOICES THAT DEPEND ON WORD CLASS
In the examples above, it is the choice between noun and verb uses that determines the spelling. Other grammatical choices can have this effect too. The two alternative spellings mentioned earlier, every day and everyday, are an example. The first acts in sentences like a noun or adverb, the second like an adjective. Compare:
(a) NOUN: Every day is different.
(b) ADVERB: Dentists recommend cleaning your teeth every day.
(c) ADJECTIVE: Everyday necessities are expensive.
In (a), every day is noun-like because it is the subject of the verb is (for more about subjects, see 12. Singular and Plural Verb Choices). In (b), the same words act like an adverb, because they give more information about a verb (cleaning) and could easily be replaced by a more familiar adverb like regularly or thoroughly (see 120. Six Things to Know about Adverbs). In (c), the single word everyday appears before a noun (necessities), giving information about it just as any adjective might (see 109. Placing an Adjective after its Noun). It is easily replaced by a more recognizable adjective like regular or daily.
Another example of a noun/adverb contrast is any more (as in … cannot do any more) versus anymore (as in … cannot go anymore). The distinction becomes important after a verb like cannot pay: not … any more means “no more than this amount”, while not … anymore means “no longer”.
Another example of an adverb/adjective contrast is on board versus onboard. I recently saw an advertisement on an aeroplane that wrongly said that something was *available onboard – using an adjective to do an adverb job. An adverb (on board) is needed here because it “describes” an adjective (available). An adjective cannot be used here because there is no noun to describe (see 6. Adjectives with no Noun 1). A correct adjective use would be onboard availability.
Slightly different is the contrast between alright and all right. The single word is either an adjective meaning “acceptable” or “undamaged”, as in The system is alright, or an adverb meaning “acceptably”, as in The system works alright. The two words all right, on the other hand, are only an adjective, and they have a different meaning from that of the adjective alright: they mean “100% correct”. Thus, Your answers are all right means that there are no wrong answers, whereas Your answers are alright means that the answers are acceptable and says nothing about how many are right.
Even more complicated are upstairs and up stairs. The single word could be either an adjective (the upstairs room) or an adverb (go upstairs) or a noun (the upstairs). The separated words are also an adverb, but with a different meaning: they mean literally climbing up some stairs. The single-word adverb upstairs, on the other hand, need not involve stairs – it just means “up above” (see 154. Lone Prepositions after BE). One could, for example, go upstairs in a lift.
The pair may be and maybe also illustrates two different word classes, this time verb and adverb:
(d) VERB: Food prices may be higher.
(e) ADVERB: Food prices are maybe higher.
In (d), the verb is are, and the adverb maybe, which comments on it, could be replaced by perhaps (indeed, in formal writing – see 46. How to Avoid “I”, “We” and “You” – it should be so replaced because maybe is conversational).
My final example is some times and sometimes: noun and adverb. They may be illustrated as follows:
(f) NOUN: Some times are harder than others.
(g) ADVERB: Sometimes life is harder than at other times.
Again, replacement is a useful strategy for distinguishing the two. The noun times, which is the subject of the verb are, can be replaced by a more familiar noun like days without radically altering the sentence, while the adverb sometimes corresponds to occasionally, and the subject of the later verb is the noun life.
USES INVOLVING “some”, “any”, “every” AND “no”
Combinations beginning with some, any, every and no are interesting. In general, these words do not make compounds, but can go before practically any noun to make what is called technically a “noun phrase”. In a few cases, however, this trend is broken. Very occasionally, these words must combine with the word after them to form a compound, and in a few other instances there is a choice between using one word or two, depending on meaning.
The compulsory some compounds are somehow, somewhere, and somewhat; the any compounds are anyhow and anywhere, while every and no make everywhere and nowhere. There is a simple observation that may help these compounds to be remembered: the part after some/any/every/no is not a noun, as is usually required, but is a question word instead. The rule is thus that if a combination starting with some or any or every or no lacks a noun, a single word must be written.
The combinations where different meanings are created by changing one word into two are someone, somebody, something, sometime, sometimes, anyone, anybody, anything, anyway (Americans might add anytime and anyplace), everyone, everybody, everything, everyday, no-one, nobody and nothing. All of the endings in these words (-one, -body, -thing, -way, -time, -place and –day) are nouns that mean the same as question words (who? what/which? how? when? and where?). For more on this equivalence, see 57. Indirect Questions in Formal Writing.
Some (tentative) meaning differences associated with these alternative spellings are as follows:
SOME TIME = “an amount of time”
Please give me some time.
SOMETIME (adj) = “past; old; erstwhile”
I met a sometime colleague
SOMETHING = “an object whose exact nature is unimportant”.
SOME THING = “a nasty creature whose exact nature is unknown”.
Some thing has bitten me!
ANYONE/ANYBODY = “one or more people; it is unimportant who”
Anyone can come = Whoever wants to come is welcome to come; Choose anyone = Choose whoever you want – one or more people.
ANY ONE = “any single person/thing out of a group of possibilities”.
Any one can come = Only one person/thing (free choice) can come; Choose any one = Choose whoever/whichever you want; choose only one.
ANY BODY = “any single body belonging to a living or dead creature”.
Any body is suitable = I will accept whatever body is available.
ANYTHING = “whatever (non-human) is conceivable/possible, without limit”.
Bring anything you like = There is no limit in what you can bring; Anything can happen = There is no limit on possible happenings.
ANY THING = “any single non-human entity in a set”.
Choose any thing = Freely choose one of the things in front of you.
EVERYONE/EVERYBODY = “all people”.
Everyone/Everybody is welcome.
EVERY ONE = “all members of a previously-mentioned group of at least three things”.
Diamonds are popular. Every one sells easily.
EVERY BODY = “all individual bodies without exceptions”.
EVERYTHING = “all things/aspects/ideas”.
Everything is clear.
EVERY THING = “all individual objects, emphasising lack of exceptions”.
Every thing on display was a gift.
NO-ONE/NOBODY = “no people”
NO ONE = “not a single” (+ noun)
No one answer is right.
NO BODY = “no individual body”.
NOTHING = “zero”.
Nothing is impossible.
NO THING = “no individual object”.
There are other problem combinations in English besides the ones I have discussed here. I have concentrated on those that have most stuck in my memory over the years. However, if any reader wishes me to consider other examples that seem important and baffling, please do not hesitate to ask via the comment facility below.