貯める[tameru] to save (i.e. in a bank)
貯金[chokin] (bank) savings
貯金通帳[chokintsuuchou] bank book
貯金箱[chokinbako] savings box
貯水[chosui] storage of water

貯水池[chosuichi] reservoir
貯蔵[chozou] storage
貯蔵タンク[chozoutanku] storage tank
定額貯金[teigakuchokin] fixed amount (postal) savings
備荒貯蓄[bikouchochiku] famine-relief fund

書留郵便[kakitomeyuubin] registered mail
定形郵便物[teikeiyuubinbutsu] standard size mail
年賀郵便[nengayuubin] New Year's mail
郵政省[yuuseishou] Ministry of Posts and Telecommunications
郵政大臣[yuuseidaijin] Minister of Posts and Telecommunications

郵税[yuuzei] postage
郵送[yuusou] mailing
郵送料[yuusouryou] freight costs
郵袋[yuutai] mailbag
郵便為替[yuubinkawase] postal money order