This is the 3938th most frequent Russian word.
дмитрию
The word "дмитрию" is the dative form of the Russian proper noun "Дмитрий" (Dmitry), meaning "to Dmitry" or "for Dmitry."
Here, "Дмитрию" is used in the dative case to indicate the recipient of the action.
Я передал книгу Дмитрию.
I handed the book to Dmitry.
In this sentence, "Дмитрию" again appears in the dative case to denote the person who is being called.
Позвоните Дмитрию, пожалуйста.
Please, call Dmitry.
Here, "Дмитрию" is in the dative case, used to indicate the entity being thanked for something.