So I'm working through a text book and wondering why I can't make the sentence "山田さんは、私の単一の友達." According to my colleague, you can, however, say "山田さんは私のある友達だ." Is it really something you can't grammatically say or does it just sound weird like saying "Yamada is my singular friend"?

  • 2
    Why are you trying to say? "one of my friends"? "my only friend"? "a friend of mine"?
    – Eddie Kal
    Jun 21, 2022 at 7:27
  • I'm not trying to say anything, just wondering why 単一 doesn't translate to "Yamada is my one friend". I also want to know why it sounds weird while ある doesn't. Is it too academic? Is there a semantic constraint that limits its usage to certain words? Etc. Can it always be replaced by a different word or is it ever necessary.
    – Hayli
    Jun 21, 2022 at 8:22
  • 4
    Both sound very weird and make little sense (even though they may be "grammatical"). Unless we know what this sentence is supposed to mean, it's impossible to fix it.
    – naruto
    Jun 21, 2022 at 8:33

1 Answer 1


Considering that you may be looking for something regarding

Yamada is my one friend

Two other options would be a better translation:



In this context, 山田さんは私のある友達だ is weird and does not make sense. I think it would be better to compare the difference between「単一」and「唯一」.

In English, we would be comparing Single 「単一」 and Only 「唯一」, which for itself may show that 「単一」 is not really appropriate in the given context.

「単一」is used to refer to the appearance of everything being the same and unified without exception, so it is used when there are many similar things that have no difference in appearance or performance, or they share similarities.

「唯一」is in a sense that there is only one in the world, that is unique.

Basically, when we have many of something/someone that are all the same/similar, we use「単一」, but if there is only one of many, so this is rare, unique, then we use 「唯一」

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