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)

一角獣[ikkakujuu] unicorn
怪獣[kaijuu] monster
食蟻獣[arikui] anteater
巨獣[kyojuu] large animal
禽獣[kinjuu] birds and animals

獣医[juui] veterinarian
獣姦[juukan] bestiality
獣肉[juuniku] animal flesh
鳥獣保護区域[choujuuhogokuiki] wildlife protection area