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)

一念発起[ichinenhokki] being resolved to (do something)
引き起す[hikiokosu] to cause
縁起[engi] omen
喚起[kanki] arousal
起きる[okiru] to get up

起上る[okiagaru] to rise
起す[okosu] to raise
起こり得る[okoriuru] to be possible to occur
起る[okoru] to occur
起つ[tatsu] to rise up