Compounds of 封

• 封緘葉書
  (n) lettercard
• 糊付き封筒
  (n) adhesive envelope
• 窓付き封筒
  (n) window envelope
  billing envelope
• 封じ込める
  (v1,vt) to shut in
  to confine
  to contain
• 返信用封筒
  (n) self-addressed stamped envelope
  SASE
• 返信料封筒
  (n) return, postage-paid envelope
• 封じ込め政策
  (n) containment policy
• 返信用の封筒
  (n) self-addressed stamped envelope
  SASE
• 言論を封殺する
  (exp) to suppress the freedom of speech