[to be delivered to someone] through someone or by way of someone. (Indicates that mail is to be delivered to a person at some other person's address.) Bill Jones is living at his father's house. Address the letter to Bill in care of Mr. John Jones.Bill said, "Please send me my mail in care of my father at his address."
Through someone, by way of someone, as in I sent the gift in care of your parents. This phrase indicates that something is to be delivered to someone at someone else's address. [Mid-1800s] Also see in charge, def. 3.