一も二も無く[ichimonimonaku] unhesitatingly
一言二言[hitokotofutakoto] a word or two
一石二鳥[issekinichou] killing two birds with one stone
一二に及ばず[ichininioyobazu] right away
一姫二太郎[ichihimenitarou] It's good to have a girl first and then a boy

うり二つ[urifutatsu] as alike as two melons (two peas in a pod)
黄道十二宮[koudoujuunikyuu] twelve signs of the zodiac
二度[futatabi] again
最小二乗法[saishounijouhou] least-squares method
三十二分音符[sanjuunibuonpu] 32nd note

ひもじい思い[himojiiomoi] state of feeling hungry
成吉思汗[jingisukan] Japanese mutton and vegetable dish
意思決定機関[ishiketteikikan] decision-making body
意思[ishi] intention
意思決定[ishikettei] decision-making

意思表示[ishihyouji] declaration of intention
一思いに[hitoomoini] instantly
引込思案[hikkomijian] reserved
危険思想[kikenshisou] dangerous thoughts
旧思想[kyuushisou] old-fashioned idea

夏至[geshi] summer solstice
夏至線[geshisen] Tropic of Cancer
夏至点[geshiten] summer solstitial point
至って[itatte] very much
至らない[itaranai] imperfect

至る[itaru] to arrive at (e.g. a decision)
至る処[itarutokoro] everywhere
至れりつくせり[itareritsukuseri] very polite
至急[shikyuu] urgent
至急便[shikyuubin] express mail