She's the only one who can do it.
Synonyms and examplesoneHe's the one person you can rely on in a situation like this.
singleYou haven't listened to a single thing I've said!
lonePolice were looking for a lone gunman.
soleHe was the sole survivor of the plane crash.
Go to the thesaurus article about these synonyms and antonyms ofonly.
Learn more
If thereare no other people or things like this one, you say it is the only one.