葉書
はがき · hagaki · JLPT N5 · noun
postcard
✉️🍃 葉書 = leaf + write: a single leaf of paper you write on
葉 (ha) means leaf and 書 (kaki, voiced to gaki) means writing. A postcard is one loose leaf with writing on it, no envelope. The kanji are ateji; the word began as 端書, a note jotted on a scrap edge of paper.