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)

ライン川[raingawa] (river) Rhine
安倍川餅[abekawamochi] rice cakes (mochi) with Kinako
川床[kawadoko] riverbed
河川[kasen] rivers
江川る[egawaru] to (try to) act like a big-shot

香川県[kagawaken] Kagawa prefecture (Shikoku)
三途の川[sanzunokawa] Sanzu River (Buddhist equivalent of the River Styx)
山川[sansen] mountains and rivers
四川[shisen] Sichuan (China)
小川[ogawa] streamlet