What is the correct pronunciation of 唯一


For the word (or composition of two words): 唯一, sometimes also written as:
唯一つ,

Two possible pronunciations come to my mind:

  * ゆいいつ [ _yuiitsu_ ] -onyomi

and

  * ただ ひとつ [ _tada hitotsu_ ] -kunyomi

**Which one is correct?** Does the last つ in written form make any difference?




唯一 and 唯一つ both work as a _no_ -adjective and a standalone adverb, but they
are different.

  * **唯一** is one word and only read as ゆいいつ in modern Japanese. (ゆいいち is another possible reading according to [this entry](https://dictionary.goo.ne.jp/jn/223584/meaning/m0u/), but I believe you can forget it)
  * **唯一つ** (with okurigana つ) is two words, ただひとつ.

They are not always interchangeable. For example you can say 唯一の生存者 ("sole
survivor") and 唯【ただ】一人【ひとり】の生存者 but not 唯一つの生存者.




唯一 and 唯一つ both work as a _no_ -adjective and a standalone adverb, but they
are different.

  * **唯一** is one word and only read as ゆいいつ in modern Japanese. (ゆいいち is another possible reading according to [this entry](https://dictionary.goo.ne.jp/jn/223584/meaning/m0u/), but I believe you can forget it)
  * **唯一つ** (with okurigana つ) is two words, ただひとつ.

They are not always interchangeable. For example you can say 唯一の生存者 ("sole
survivor") and 唯【ただ】一人【ひとり】の生存者 but not 唯一つの生存者.

