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“Only” has various adverb uses, and can also be an adjective or conjunction
THE MULTI-USE NATURE OF “ONLY”
Most experienced users of English would be very quick to say, if asked whether they were familiar with the basic word only, that they certainly were. If they were further asked to say what they knew about this word, they would surely give a good description of what it means and where in a sentence it is typically used. However, I am not so sure that the full range of grammatical possibilities would be easily described.
Only in fact occurs in quite a wide range of grammatical structures, and is consequently a good example of what I call a “multi-use” word (see 3. Multi-Use Words). The present post aims to highlight some of the more esoteric grammatical uses. This is a similar kind of approach to that taken in various other parts of this blog that make a detailed study of a small familiar word (for a list, click on the SPECIFIC WORDS tab above).
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FUNDAMENTAL MEANINGS
As a preliminary, a brief look at the main meanings of only may prove useful. The adjective meaning is “not accompanied by other instances or amounts”. For example, both the only explanation and the only two explanations mean no other explanations exist.
Common adjective synonyms are sole and lone. Like them, only cannot be alone after BE or similar (see 184. Adjectives with Limited Mobility, #3), but can combine there with the … one(s) (see 263. Uses of “One” and “Ones”, #6). One adjective that is not a synonym is unique. It combines the meaning of only with the idea of “unequalled” (see 284. Words with a Surprising Meaning, #13).
Sometimes adjectival only is necessitated by the choice of noun (i.e. it is “collocational” – see 16. Ways of Distinguishing Similar Words, #5). For example a child without siblings is usually an only child.
As an adverb only is again often found before a noun (see 313. Adverbs Linked Closely to a Noun, #2). It must precede any use of the, a(n) or similar. Thus it is an adverb in only the explanation. It carries the same meaning as the adjective, but also one of various other meanings, depending on the context. For example, only one week would variably suggest:
INSUFFICIENT: schooling time in a year
IMPRESSIVE: time taken to write a dissertation
UNIMPORTANT: time saved over ten years
These extra meanings make adverbial only useful in data interpretations (see 115. Surveying Numerical Data). Sometimes, though, there can be uncertainty about which meaning applies, so that a more precise synonym becomes advisable. For example, just is more suggestive of impressive achievement, while merely can more definitely indicate unimportance.
One other notable use of adverbial only is before adverbial expressions indicating time of occurrence. In past ones, such as only last month or only just, the time is implied to be surprisingly recent; in future ones, such as only tomorrow, later than desired. Only ever means “always without exception” (see 272. Uses of “Ever”).
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SPECIAL GRAMMATICAL USES
Probably the most familiar grammatical aspect of only, besides its adjective / adverb usability, is the multiplicity of sentence positions that the adverb use can occupy, with consequent potential for misunderstandings. I exclude it here because it is widely described elsewhere. Six other uses are as follows.
1. With a Conjunction
Adverbial only can precede some conjunctions to limit their meaning. For example, only when… means no other times are possible besides the one specified; only because… works similarly with reasons or causes; and only if… does the same with conditions (see “Open Conditions” in 179. Deeper Meanings of “if”).
It is mainly “subordinating” conjunctions that can follow only (i.e. not those that must go between two linked statements, like and, but and or – see 174. Eight Things to Know about Conjunctions, #3). The commonest possibilities express time (when, while, after, until, since), cause (because, since, seeing that), condition (if, provided that) or purpose (so that, in order to). Combination with although is unlikely.
When only follows a conjunction, it is usually combining with the next word rather than the conjunction. However, one exceptional case involves if (if only…) to express a wish for an unfulfilled past or present, or an unlikely future. The tense choices are the same as after wish that… (see 254. Tricky Word Contrasts 10, #6).
There is also a historical description use that perhaps expresses a less personal, more general regret (see 282. Features of History Writing, #12):
(a) If only the dangers of smoking had been known, much suffering would have been avoided.
For more on wishing, see 238. Using a Verb to Perform its Action, #6.
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2. Starting a Sentence
After a starting only, some or all of the accompanying verb often goes before its subject, like in direct questions (so-called “inversion”):
(b) Only children DO they allow inside.
(c) Only when vaccination is possible WILL the virus BE DEFEATED.
In (b), the “auxiliary” verb do precedes they, the subject of allow. In (c), will precedes the virus, the subject of will be defeated. The earlier verb is in (c) does not precede vaccination because it follows when, which postpones the influence of only (see 37. Subordination).
The main situation where no inversion follows a starting only is when the subject of its accompanying verb follows immediately:
(d) Only children can enter.
When only is not the first word, inversion is not normally allowed. A major exception, however, is in some sentences starting with not only…. This expression introduces information implied to be already familiar to the addressee, the main point of the sentence being in a later but (also) statement (see 64. Double Conjunctions):
(e) NOT ONLY will the virus be defeated, BUT the world’s economy will also recover.
Here, two different verbs are used (will be defeated, will recover), with different subjects (virus, economy). In such situations, not only needs to start the sentence and requires inversion.
The situation is slightly different when two different verbs have the same subject (one expressed with a pronoun):
(f) Not only will the virus be defeated but it will never reappear.
Again, with not only at the start, inversion is necessary. However, such sentences also allow not only to be later, ruling out inversion and making the pronoun optional: The virus will not only be…but (it) will….
A third possibility is two different subjects with the same verb:
(g) Not only the virus will be defeated but also economic instability.
Here, not only must start, but inversion is optional. The verb is usually mentioned only once, either between the two subjects or after them. For more about inversion outside questions, see 307. Word Order Variations, #3.
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3. Before “to”
Only can precede a to statement at the end of a sentence:
(h) Motorways speed up traffic movement, only to cause jams elsewhere.
In such sentences, the to statement expresses an unexpected and often undesirable consequence of what is said before it. The subject of the to verb will be the same as that of the earlier, main verb (here motorways), unless a different subject is mentioned in a for phrase after only.
For a fuller description of this use of only, see 247. Exotic Grammar Structures 6, #1.
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4. Indicating an Exception
Exceptions are members of a general class that contradict or fail to follow a rule or generalization about it. Their mention usually needs an accompanying statement of the rule or generalization, either in the same sentence or separately beforehand – rather as happens with examples (see 1. Simple Example-Giving) or lists (see 122. Signpost Words in Multi-Sentence Lists).
Only is useful for naming all (not some) of the exceptions to a generalization expressed in a preceding sentence:
(i) Few creatures survive extreme cold. Only certain micro-organisms have this ability.
As this suggests, the exception wording (underlined) is usually a noun phrase, with only directly before it. The rest of the sentence often just paraphrases the main part of the rule, but not always (see 215. Naming Exceptions, under “Other Options”).
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5. As a Conjunction
This is a rather informal use of only, uncommon in professional writing. Some books say it means but, but I think it is narrower. Compare:
(j) Cycling has numerous benefits, only there is a risk of accidents.
(k) Accommodation is cheap, only the location is isolated.
(l) Train travel would be easy, only the state will not subsidise it.
In all these, only is easily replaceable by but: both are “coordinating” conjunctions (located between two linked statements, unable to go before them as although can). The sole meaning difference seems to be that only is clearer that no other possibility exists. With but, this interpretation is possible but not inevitable.
In (j), the meaning is very similar to the exception-showing one described above: the words after only name a disadvantage outside a general advantageous trend. In (k), a single advantage (cheap) is compared with a single disadvantage (isolated), so a contrast rather than exception is being indicated. Sentence (l) mentions an unreal idea using would (easy train travel), then gives a reason for the unreality.
Although but can usually replace only, the reverse is not always the case. Only but, for example, is possible in the following, despite the similarity to (k):
(m) The storm was fierce but the ship survived.
A requirement for using only in sentences like (j) and (k) is perhaps that it should introduce something undesirable. The absence of such an idea in (m) seems to explain why but is necessary there. Only would sentences like (l) seem to allow mention of something desirable after only, as in the following rewording of (l):
(n) Train travel would be difficult, only the state is subsidising it.
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6. Before “too” + Adverb / Adjective
Only too is close in meaning to “very”. There are two uses. One combines the “very” meaning of too with the idea of “disastrous”:
(o) Addiction can develop only too easily.
Here, only too easily indicates ease that is so great as to be disastrous. Similarly, is only too true indicates disastrously definite truth.
This use of only too… can be paraphrased with all too… . It is unlikely to start a sentence. Only too… at the start of a sentence is likely to have a more standard, alternative-denying meaning of only:
(p) Only too late were the dangers understood.
Here, the denied alternatives are other times, such as “early”, “in time” and “late”.
The second use of only too… meaning “very” accompanies adjectives expressing a positive human state, such as happy:
(q) The villagers were only too happy to demonstrate their skills.
Other possible adjectives here include eager, glad, keen, pleased, ready and willing.
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7. In Predictions
Only can follow predictive will (or equivalent: see 147. Types of Future Meaning, #1) to predict occurrence of something unwanted instead of what is planned. A common usage is …will only make matters worse.
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