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)

お大事に[odaijini] take care of yourself
暗黒大陸[ankokutairiku] Dark Continent (i.e. Africa)
伊勢大神宮[isedaijinguu] the Grand Shrines of Ise
伊勢大廟[isetaibyou] the Grand Shrines of Ise
偉大[idai] greatness

医科大学[ikadaigaku] medical school
医大[idai] medical university
井の中の蛙大海を知らず[inonakanokawazutaikaiwoshirazu] parochial
一大[ichidai] one large ...
一大事[ichidaiji] serious affair

おけさ節[okesabushi] style of Japanese folk song associated with Niigata Prefecture
双節棍[nunchaku] nunchaku (two linked fighting sticks)
一音節[ichionsetsu] monosyllable
一節切り[hitoyogiri] one-jointed bamboo musical instrument
音節[onsetsu] syllable

鰹節[katsubushi] katsuobushi
環節[kansetsu] segment (of worm)
関節[kansetsu] joints (knee joint, elbow joint, etc.)
関節リューマチ[kansetsuryuumachi] rheumatoid arthritis
関節炎[kansetsuen] arthritis