noun
lettercard
A postal item that combines a letter sheet with a prepaid postage stamp, sealed on three sides; used for brief correspondence.
封緘葉書は、手紙のように封をして送れるはがきです。
A lettercard is a postcard that can be sealed and sent like a letter.
A regular postcard, not sealed; 封緘葉書 is a specific type that can be sealed.
Compound of 封緘 (sealing) and 葉書 (postcard).