海亀[umigame] sea turtle
亀の子[kamenoko] young turtle (tortoise)
亀の手[kamenote] barnacle
亀鑑[kikan] pattern
亀甲[kikkou] tortoise shell

亀頭[kitou] glans (esp. glans penis)
亀裂[kiretsu] crack
水亀[ishigame] any turtle of the genus Mauremys (esp. the Japanese pond turtle, Mauremys japonica)
盲亀[mouki] blind turtle

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