御中[onaka] stomach
御話中[ohanashichuu] busy (phone)
アル中[aruchuu] alcoholism
π中間子[paichuukanshi] pi meson
暗中[anchuu] in the dark

暗中摸索[anchuumosaku] groping in the dark
意中[ichuu] one's mind
意中の女[ichuunoonna] sweetheart
井の中の蛙大海を知らず[inonakanokawazutaikaiwoshirazu] parochial
一日中[ichinichijuu] all day long

堅魚[katsuo] skipjack tuna
堅い[katai] hard
堅果[kenka] nut
堅苦しい[katakurushii] formal
堅固[kengo] solid

堅持[kenji] holding on to
堅城[kenjou] strong fortress
堅陣[kenjin] stronghold
堅調[kenchou] bullish
堅忍[kennin] perseverance