一封[ippuu] sealed letter
開封[kaifuu] unsealed letter
完封[kanpuu] complete blockade (seal)
旧封[kyuuhou] former fief
厳封[genpuu] sealing hermetically

言論を封殺する[genronwofuusatsusuru] to suppress the freedom of speech
御封[gofu] talisman
再封鎖[saifuusa] reblocking
三封[sanpuu] forced out on third
全封地[zenhouchi] the whole fief

緘口令[kankourei] gag order
緘口[kankou] keeping silent
緘黙[kanmoku] keeping silent
封緘[fuukan] seal
封緘葉書[fuukanhagaki] lettercard

瑶緘[youkan] your letter
緘する[kansuru] to shut
緘口令を敷く[kankoureiwoshiku] to impose a gag order
緘黙症[kanmokushou] mutism