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)

黄緑[kimidori] pea green
黄緑色[ouryokushoku] yellow-green
灰緑色[kairyokushoku] greenish gray
黒緑[kuromidori] blackish green
常緑[jouryoku] evergreen

常緑樹[jouryokuju] evergreen tree
新緑[shinryoku] fresh verdure
濃緑色[nouryokushoku] dark green
万緑[banryoku] myriad green leaves
葉緑素[youryokuso] chlorophyl