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)

悪足掻き[waruagaki] useless resistance
一挙手一投足[ikkyoshuittousoku] slight effort
一足[issoku] pair (footwear)
一足[hitoashi] step
一足先[hitoashisaki] one step ahead

一足飛び[issokutobi] (at) one bound
逸足[issoku] fast runner
右足[migiashi] right foot
運動不足[undoubusoku] insufficient exercise
栄養不足[eiyoubusoku] malnutrition