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.

  • 7
    Don'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. Commented Nov 9, 2017 at 16:19
  • 11
    There 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
    Commented Nov 9, 2017 at 17:28
  • 8
    I 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
    Commented Nov 9, 2017 at 18:57
  • 6
    @elmer007 It must be this episode of Wheel of Fortune. In the toss-up, letters are revealed one letter at a time.
    – Laurel
    Commented Nov 9, 2017 at 19:38
  • 9
    The 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
    Commented Nov 10, 2017 at 4:29

4 Answers 4


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.

  • 1
    The first example is sorta weird, because it seems like "only" and "child" are more separated than usual.... Commented Nov 9, 2017 at 17:32
  • 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
    Commented Nov 9, 2017 at 18:43
  • "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
    Commented Nov 10, 2017 at 15:11
  • @Deolater Thanks for that, I couldn't find the right way to put it. Commented Nov 12, 2017 at 17:36

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.

  • 1
    This 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
    Commented Nov 9, 2017 at 16:54
  • 8
    Only one Eiffel tower> Well, there are several smaller-scale replicas around the world, which could be considered other Eiffel towers. Commented Nov 9, 2017 at 17:50
  • 11
    There's an Eiffel Tower in Las Vegas. Whether or not this is true, it's still grammatical to say it. Commented Nov 9, 2017 at 22:00
  • 11
    @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
    Commented Nov 9, 2017 at 22:03
  • 5
    @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. Commented Nov 10, 2017 at 12:18

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.


What about this:

Paniz isn't spoiled at all, even though she's an only child. [Or should it be "the" only child?]

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