英吉利[igirisu] Great Britain
吉利支丹[kirishitan] early Japanese Christianity (from the later Muromachi period)
成吉思汗[jingisukan] Japanese mutton and vegetable dish
吉凶[kikkyou] sunshine and shadow
吉祥[kisshou] lucky omen

吉徴[kicchou] lucky omen
吉報[kippou] good news
吉備団子[kibidango] sweet dumpling made with mochi flour and (sometimes) millet flour (famous product of Okayama)
吉丁虫[tamamushi] jewel beetle
石部金吉[ishibekinkichi] man of incorruptible character

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