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)

丸柱[marubashira] column
火柱[hibashira] pillar of fire
蚊柱[kabashira] mosquito swarm
貝柱[kaibashira] adductor muscle
巻柱[makibashira] gold-covered woodwork at a temple in Hiraizumi

魂柱[konchuu] sound post (violin, etc.)
支柱[shichuu] prop
斜角柱[shakakuchuu] oblique prism
人柱[hitobashira] human pillar
水銀柱[suiginchuu] column of mercury

兎や角言う[toyakakuiu] to say all kinds of things
まっ四角[masshikaku] square
アフリカの角[afurikanotsuno] horn of Africa
一角[ikkaku] corner
一角の人物[hitokadonojinbutsu] somebody (important)

一角獣[ikkakujuu] unicorn
烏犀角[usaikaku] black rhinoceros horn
鋭角[eikaku] acute angle
外角[gaikaku] outside corner
町角[machikado] street corner