Why do we use "an" in the phrase "an only child"?



I remember an episode from a game show. I am pretty sure it was "Wheel of Fortune." The task was to restore missing letters: an **ly child. The contestant answered "an ugly child", but the correct answer is "an only child." Moreover, I asked some people who know English well, and they replied that "an only child" is the only possible solution, though they didn't explain their choice in any way.

As for me, I consider the phrase "an only child" a little bit weird. "An ugly child" sounds nice for me, because he/she can be any of millions of such children, we just didn't specify the person we bear in mind. On the other hand, "only child" is a well defined person. There are no other children in the family; the child is single so we know whom we are talking about. So for me, it's like saying "a sun" or "a hell" or "an Eiffel Tower" which, as I know, are wrong constructions.

Can anyone explain why do we use indefinite article here? Does it have any particular or specific meaning?

Please don't blame it too much because in my native language there are no articles. Thanks for help.


Posted 2017-11-09T16:02:00.187

Reputation: 1 498

7Don't get too bogged down in analysing the "structure" of the collocation *[an] only child*. There are "similar" adjectival usages, such as *Her only fault is that she's ugly*, but only *only child* gets its own dedicated entry in the full subscription-only OED. And as for your "Wheel of Fortune" context, whereas it's quite true that *only child* is far more common than *ugly child*, this doesn't mean the latter is "incorrect" - it just means we have reason to use the former far more often. But we also say, for example, *He is the only child of wealthy parents*. – FumbleFingers Reinstate Monica – 2017-11-09T16:19:30.170

1...anyway, I'm voting to close as "Unclear" because I don't see why it would have made any difference if the cited "game show" context had asked contestants to fill in the blanks with *the __ly child*. – FumbleFingers Reinstate Monica – 2017-11-09T16:23:42.643

10There are lots of only children (and ugly children), but only one only child per set of parents. So: Charlie is an only child; he's the only child of Alice and Bob. – anomaly – 2017-11-09T17:28:37.683

8I doubt that it was "Wheel of Fortune." Is there a possible scenario on the show where the "n" in "an" is shown but the "n" in "only" is not? – elmer007 – 2017-11-09T18:57:13.143


@elmer007 It must be this episode of Wheel of Fortune. In the toss-up, letters are revealed one letter at a time.

– Laurel – 2017-11-09T19:38:52.457

1@Laurel Yes, good point, and good research! (Laurel's link shows that the episode in the question is from 11 April 2002) – elmer007 – 2017-11-09T19:41:15.760

9The reason that an only child is “the” solution here and an ugly child is a bad guess has nothing to do with English grammar. Rather, it is because an only child is a rather-common phrase in English, the sort of thing likely to come up in Wheel of Fortune, while an ugly child, while a perfectly reasonable and grammatical phrase, isn’t particularly common. In short, an only child is the “only possible solution” because it is the only one that fits the format of the show (and possibly the stated category). – KRyan – 2017-11-10T04:29:41.897

1@FumbleFingers I think your missing the point of the question here, which is, I believe, that it is unusual to use an for a unique readily identifiable thing. We would expect a definite determiner such as the, her etc. [The reason of course is that only child is a compound noun meaning the only child of a particular couple. There are obviously many only children everywhere. Ugly child, holy child etc are not compound nouns]. – Araucaria - Not here any more. – 2017-11-10T09:19:49.747

To clarify: I indeed wanted to know why in this particular "Wheel of Fortune" task the indefinite article ("an only child") was used and not the definite article. I'm sorry if this is not very clear from the question itself. Deolater's answer is really helpful and much appreciated. – Alexander – 2017-11-10T09:32:04.600

Pls edit your question to emphasize that you wanted to know why we don't say "the only child". That will help voters and readers, now this is a 'hot question'. – Qsigma – 2017-11-10T10:58:15.123

I believe it is not incorrect to say "A sun" or "A hell" or "an Eiffel tower." There are many suns and many planets have a sun. Some might have two or more suns. If I'm living in my own personal hell, then that is a hell. If they built another Eiffel tower, each would be an Eiffel tower. We typically see "the" in these situations because it colloquially refers to a specific familiar thing. Note we don't usually see "the" with hell - it's either "a hell" or just the name "Hell." – taz – 2017-11-10T18:13:05.180

Update to my previous comment: I was technically incorrect about the sun, because, as another comment pointed out, in scientific terminology, planets have stars, not suns. – taz – 2017-11-10T18:35:36.423



In this case the phrase "an only child" is correct because there are, in fact, many "only" children. "Only child" is a term that just means a person who does not have brothers or sisters. Many millions of people have no siblings, so each of these people is an only child.

In the context of talking about a specific family (or group) with only one child, you use "the".

Rachel, the only child present, toasted with orange juice rather than champagne.

On the other hand, when discussing (as a generality) people without siblings, you would use "an".

I was surprised to learn that Billy had no siblings. His care for younger children was not what I had been led to expect from an only child.


Posted 2017-11-09T16:02:00.187

Reputation: 851

1The first example is sorta weird, because it seems like "only" and "child" are more separated than usual.... – Feathercrown – 2017-11-09T17:32:38.353

13@Feathercrown Indeed. In the first example I am not using the compound noun "only child", but using the words "only" and "child" in their usual separate meanings. It's a bit like the sentence "The old man the boats" in that it can slightly defeat your initial expectation of what "only child" (or "old man") means. – Deolater – 2017-11-09T18:43:15.450

"An only child" is somewhat of an isolated case, as well. You don't typically use "only" in this fashion with other nouns; using "an only cat" to refer to a person's only pet is stilted, at best. – chepner – 2017-11-10T15:11:35.467

@Deolater Thanks for that, I couldn't find the right way to put it. – Feathercrown – 2017-11-12T17:36:19.043


You almost always use an indefinite article when referring to people. You wouldn't/couldn't say "She is child." You must say "She is a child."

She is a smart child. She is an awful child. She is an only child. (She has no siblings.) The right answer was "an only child" because it is a common phrase. "an ugly child" certainly works too.

Also, you can say "a sun" because there are other suns and there are other moons for other solar systems. You can also say "a hell". There are many hells. This prison is a hell no one deserves.
It's true you cannot say "an Eiffel Tower" because there is only one.

Jess Z.

Posted 2017-11-09T16:02:00.187

Reputation: 170

1This is certainly correct, but I think OP's question was why use the indefinite article "an" instead of the definite article "the". "The only child" would be fine, in the right context. – Andrew – 2017-11-09T16:54:13.197

8Only one Eiffel tower> Well, there are several smaller-scale replicas around the world, which could be considered other Eiffel towers. – Sean Burton – 2017-11-09T17:50:20.127

No, Eiffel Tower is a proper noun, there is only one. There maybe replicas or duplicates of it, but there is only one Eiffel Tower. – T.J.L. – 2017-11-09T20:36:18.213

11There's an Eiffel Tower in Las Vegas. Whether or not this is true, it's still grammatical to say it. – Dawood ibn Kareem – 2017-11-09T22:00:54.507


@T.J.L. Neither being a proper noun nor being unique has any direct bearing on the use of the article. One can dream up an Eiffel Tower of wood, or wish for an Eiffel Tower that were not so crowded. See at EL&U Indefinite article and people's names for example.

– choster – 2017-11-09T22:03:44.113

@T.J.L. i think you're thinking of when there are many replicas and fakes of something, but you use the definite article to let people know you mean the Eiffel Tower – worc – 2017-11-10T00:18:14.350

surprisingly your answer makes perfect sense and the one selected as an "answer" does not, surprising because of the votes difference – Vikram – 2017-11-10T09:47:27.040

The sun is a star. But there is only one sun. people mistakenly use sun for star often, but that doesn't make it correct. Some with solar system, there is only one such system (our star system), but there are many other star systems. For moons its a bit more complicated, The Moon is only our own moon, while other moons c ertainly exist (e.g. the galilean moons). depending on the context, you can say "An Eiffel tower", e.g. "What model did he get?" - "He got an Eiffel Tower" (sure, there is some implied context, but it works). – Polygnome – 2017-11-10T11:10:12.450

1@Vikram The accepted answer makes perfect sense. "Only child" is an idiomatic phrase meaning "person who has no siblings". This answer, on the other hand, misses that point and treats "only" as just an ordinary adjective. "Only child" isn't comparable to "smart child" because, for example, you could say "Rover is a smart dog" but you wouldn't say "Rover is an only dog" to mean that Rover's owner has no other dogs. If Mr Smith is the teacher at a school that has just one teacher, he is the only teacher, but not an only teacher. – David Richerby – 2017-11-10T11:59:34.207

1@Andrew But "the only child" almost always means "the unique child in the current situation", e.g., "Jenny was the only child in the room -- everyone else was an adult." You can contrive situations where it means "the unique child with no siblings" (e.g., "I've heard that one of you has no siblings. Which of you is the only child?") but they seem rare. In particular, if you just said "Jenny is the only child in the room", everybody would assume you meant that the other people in the room weren't children, not that the other people had siblings. – David Richerby – 2017-11-10T12:04:27.057


@Polygnome Sorry, but in non-scientific writing, "sun" is commmonly used to refer to any star, especially one that resembles our sun (see, e.g., Merriam-Webster defn 1b, Oxford Dictionaries defn 1.1), and it's fairly common to refer to other planetary systems as "solar systems", too.

– David Richerby – 2017-11-10T12:18:36.657

1@Polygnome Also, you are not entirely correct about the scientific usage either. The solar system is not an instance of a star system--it is an instance of a planetary system. A star system is a group of two or more stars. – called2voyage – 2017-11-10T14:07:41.627

@ Sean Burton But it would again depend on a context: if one thinks of it as a tower built by Eiffel, it again will be 'only one Eiffel Tower' at least relative to the replicas in question. Would not it? – Giorgi – 2017-11-11T07:33:42.613


It is the indefinite article because you're dealing with the vague concept of 'only child-ness', not a specific instance of it.

Think about 'it is a tree' - tree is indefinite because you haven't specified which tree or sort of tree. Had you been speaking about a specific tree before, you could use 'the tree' meaning 'the one i was talking about earlier'.

You can say 'she is the only child of {particular person}' because now you've added enough information to make it a very specific instance.


Posted 2017-11-09T16:02:00.187

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