御猪口[ochoko] small cup
片口鰯[katakuchiiwashi] Japanese anchovy (Engraulis japonica)
白口[shiroguchi] white croaker (Pennahia argentata)
悪たれ口[akutareguchi] abuse
悪口雑言[akkouzougon] all kinds of malicious gossip

異口同音[ikudouon] in concert
異口同音に[ikudouonni] in one voice
ひと口[hitokuchi] mouthful
一口商い[hitokuchiakinai] an immediate definite deal
一口同音[ikkudouon] reading in unison

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