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)

ドイツ民主共和国[doitsuminshukyouwakoku] German Democratic Republic (i.e. former East Germany)
移民[imin] emigration
漢民族[kanminzoku] Chinese people
窮民[kyuumin] poor people
区民[kumin] ward residents

愚民[gumin] ignorant people
軍民[gunmin] the military and civilians
県民[kenmin] citizens of a prefecture
県民会館[kenminkaikan] prefectural meeting hall
原住民[genjuumin] native people