IPA: /ˌæd.rəˈsiː/
KK: /ædˈrɛsi/
A person or group to whom a message, letter, or other communication is directed.
The addressee of the letter was surprised to receive it.
Addressee → It is formed from "address" (from Old French *adresser*, meaning to direct or to put in a certain direction) and "-ee" (a suffix used to indicate a person who is the recipient of an action). The word "addressee" refers to the person to whom something is directed or addressed.
Think of someone being 'directed' ('address') and the '-ee' meaning a person who receives that direction. An addressee is simply the person to whom something is addressed.