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

一六銀行[ichirokuginkou] pawnshop
一六勝負[ichirokushoubu] gambling
五臓六腑[gozouroppu] the internal organs
三十六計[sanjuurokkei] the 36 (ancient Chinese military) strategies (of which the last resort was said to be beating a retreat)
三面六臂[sanmenroppi] rush of business

四六時中[shirokujichuu] around the clock
十六[juuroku] 16
十六音符[juurokuonpu] 16th note
十六夜[izayoi] sixteen-day-old moon
上方贅六[kamigatazeiroku] people of the Kyoto area

まっ四角[masshikaku] square
一天四海[ittenshikai] the world
下四半期[shimoshihanki] last quarter (of the year)
弦楽四重奏曲[gengakushijuusoukyoku] string quartet
再三再四[saisansaishi] repeatedly

三寒四温[sankanshion] alternation of three cold and four warm days
四つ[yottsu] four
四つんばい[yotsunbai] (crawl) on all fours
四つ角[yotsukado] four corners
四つ足[yotsuashi] four-footed (animal)

何時もより[itsumoyori] more than usual
御三時[osanji] three-o'clock snack
ある時[arutoki] once (i.e. "once, when I was studying ..")
安静時[anseiji] resting
安土桃山時代[azuchimomoyamajidai] Azuchi-Momoyama period (approx. 1558-1600 CE)

暗黒時代[ankokujidai] Dark Ages
育児時間[ikujijikan] nursing time
ひと時[ittoki] moment
一時に[ichidokini] at the same time
一時間[ichijikan] one hour