This is the 75th most frequent Croatian word.
tko
"Who"
Here, 'tko' is used in a negative expression to imply no person is available or responsible.
Nema tko drugi da završi zadatak.
There is no one else to finish the task.
Here, 'tko' is used as an interrogative pronoun to ask about someone's identity.
Tko si ti?
Who are you?
In this sentence, 'tko' introduces a subordinate clause and refers to an unknown person.