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)

阿吽の呼吸[aunnokokyuu] the harmonizing, mentally and physically, of two parties engaged in an activity
阿呆陀羅[ahondara] fool
阿蘭陀[oranda] Holland
阿ねる[omoneru] to flatter
阿多福[otafuku] homely woman (esp. one with a small low nose, high flat forehead, and bulging cheeks)

阿鼻叫喚[abikyoukan] agonizing cries
阿片窟[ahenkutsu] opium den
阿弥陀[amida] Amitabha
阿呍[aun] Om
阿諛[ayu] flattery