lettercard
/ˈlɛtərˌkɑrd/
noun
- A postal card that is folded and sealed, designed to be written on and sent by mail at a reduced rate.
- She sent a lettercard from her vacation because it was cheaper than a regular letter.
- The museum gift shop sold vintage lettercards with beautiful artwork.
- He wrote a quick note on a lettercard and mailed it that afternoon.