This is the 998th most frequent Estonian word.
kellelegi
"To someone" or "for someone."
In this sentence, 'kellelegi' is used to indicate the recipient (in the allative case) of the action.
Ma andsin kellelegi raamatu.
I gave a book to someone.
Here, 'kellelegi' specifies an unspecified individual from the audience being addressed.
Küsimus esitati kellelegi publikust.
The question was posed to someone in the audience.
In this case, 'kellelegi' is used to define the recipient as an undefined, significant person.