洋よう形けい

noun

Western-style envelope (long-side opening)

Refers to Japanese Western-style envelopes that open on the long side, numbered 0–7 with different sizes. Used in postal and stationery contexts.

• 洋よう形けいの封ふう筒とうを買かってきてください。

  Please buy some Western-style envelopes.

• 洋よう形けい0号ごうは一いち番ばん小ちいさいサイズです。

  Western-style size 0 is the smallest size.