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)

四面楚歌[shimensoka] being surrounded by enemies on all sides
楚楚[soso] graceful

清楚[seiso] neat and clean
楚蟹[zuwaigani] snow crab (Chionoecetes opilio)

哀歌[aika] lament (song)
愛唱歌[aishouka] (one's) favourite song
詠歌[eika] poem (esp. tanka)
艶歌[enka] enka
応援歌[ouenka] rooters' song

歌い合う[utaiau] to sing responsively
歌い上げる[utaiageru] to sing at the top of one's voice
歌詠み[utayomi] tanka composer
歌会[utakai] poetry party or competition

その反面[sonohanmen] on the other hand
委細面談[isaimendan] details when I see you
一面[ichimen] one face
一面観[ichimenkan] one-sided view
一面識[ichimenshiki] (a) passing acquaintance

隠面[inmen] hidden surface
右面[umen] right side
液面[ekimen] liquid surface
凹面[oumen] concavity
凹面鏡[oumenkyou] concave mirror