IPA: /ˈpoʊst.kɑrd/
KK: /ˈpoʊstˌkɑrd/
A card made of thick paper or cardboard that you can write on and send by mail without needing an envelope.
I sent my friend a postcard from my vacation in Hawaii.
Postcard → It is formed from "post" (from Latin *postis*, meaning after or behind) and "card" (from Old French *carte*, meaning a piece of paper). The word "postcard" refers to a card sent through the mail after being written on, typically without an envelope.
Think of sending a message on a 'card' that is delivered 'after' it is written — that's why a postcard is a card sent through the mail.