This is the only useful book available here.

I am the only child of my parents.

No other one can be found on the island. The hermit is the sole inhabitant there.

This widow lived all by herself. Her sole companion was her maid servant.

The two women were the sole survivors from the air crash.

Phil is the sole heir to all that property.

Are these two words interchangeable in the examples above?

  • 2
    I believe that you already know it, but I will make a note anyway, just in case. "Sole" is an adjective, while "only" can be an adjective, an adverb, or a conjunction. Consequently, we can't always replace "only" with "sole". Jim has already explained nicely why it's only #5 in your examples that you couldn't use either "sole" or "only". Commented Mar 24, 2014 at 14:52
  • @DamkerngT. Doesn't the last sentence in your comment need a preposition like "in" at the end? Like into "Jim~~either "sole" or "only" in/for". I would just like to ask a question to you. Commented Jun 7, 2017 at 8:27

2 Answers 2


"Sole" means "the only one". "Only" means the set is restricted to the identified members, but there could be more than one in that set.

That is, in all your examples, you could use either "sole" or "only" and the sentence would mean the same thing, EXCEPT for #5. You cannot say, "The two women were the sole survivors" because "sole" means only one. Effectively you're saying, "Only one person survived: Sally and Jane", which makes no sense.

That said, we commonly say "He was the sole survivor ..." or "the sole heir". But I've never heard someone say, "It was the sole useful book ..." or "I am the sole child ..." I'm hard pressed to think of a rule for when one is used versus the other in cases where either is valid.

  • I think "sole useful book" could be because there's an extra adjective? I can't think of any examples where you would use sole before another adjective. So we'd say "I'm the sole survivor" but not "I'm the sole surviving passenger". Commented Mar 24, 2014 at 15:04
  • 1
    Not so certain about "sole child". It doesn't sound quite as wrong to me (provided it was followed by some kind of clarifier, like "of my parents" or "in my class" (the latter meaning that the other class members are adults)). Perhaps it's just that "only child" is such a stock phrase? Commented Mar 24, 2014 at 15:06
  • @starsplusplus Yes, I suspect it's really a matter of idiomatic speech. There are some sentences one could say that are 100% grammatically correct and use all words with correct definitions ... but it's just that no one says it that way.
    – Jay
    Commented Jul 17, 2020 at 13:09

Can “sole” really not have a plural referent? For me, number 5 does not sound wrong. And it’s possible to find published examples that support this. Here are two from Google Books for “sole descendants”:

H. G. Wells “The Time Machine” p. 49:

But, gradually, the truth dawned on me: that Man had not remained one species, but had differentiated into two distinct animals: that my graceful children of the Upper-world were not the sole descendants of our generation, but that this bleached, obscene, nocturnal Thing, which had flashed before me, was also heir to all the ages.

And also Charlotte Bronte, “Jane Eyre”:

I am obscure: Rivers is an old name; but of the three sole descendants of the race, two earn the dependent’s crust among strangers, and the third considers himself an alien from his native country – not only for life, but in death.

There are plenty of more recent examples of this as well.

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