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)

ひもじい思い[himojiiomoi] state of feeling hungry
成吉思汗[jingisukan] Japanese mutton and vegetable dish
意思決定機関[ishiketteikikan] decision-making body
意思[ishi] intention
意思決定[ishikettei] decision-making

意思表示[ishihyouji] declaration of intention
一思いに[hitoomoini] instantly
引込思案[hikkomijian] reserved
危険思想[kikenshisou] dangerous thoughts
旧思想[kyuushisou] old-fashioned idea