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)

夷国[ikoku] land of the barbarians
夷人[ijin] barbarian
夷俗[izoku] customs of the barbarians
夷狄[iteki] barbarians

蝦夷[ezo] peoples formerly of northern Japan with distinct language and culture (i.e. the Ainu)
勤皇攘夷[kinnoujoui] loyalty to the emperor and expulsion of the foreigners
蕃夷[bani] savages
攘夷[joui] expulsion of the foreigners