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)

烏有に帰する[uyuunikisuru] to be reduced to ashes
烏有先生[uyuusensei] fictitious person
恩が有る[ongaaru] to be in one's debt
価値有る[kachiaru] valuable
含有[ganyuu] contain

含有量[ganyuuryou] content (of a mineral, etc.)
享有[kyouyuu] possession
共有[kyouyuu] share
共有財産[kyouyuuzaisan] community property
共有者[kyouyuusha] joint owners