This is the 3394th most frequent Turkish word.
kimdir
"Kimdir" means "Who is it?" or "Who is he/she/they?" in English.
In this sentence, 'kimdir' is used to inquire about the identity of the person responsible for an action.
Bu evi yaptıran kişi kimdir?
Who is the person who had this house built?
Here, 'kimdir' is utilized to ask about the identity of someone described or referenced.
Kitapta bahsedilen yazar kimdir?
Who is the author mentioned in the book?
In this example, 'kimdir' is applied to question the identity of a historically significant person.