ちょっと一杯[chottoippai] let's have a quick drink
ばつ一[batsuichi] being once divorced
一向[hitaburu] nothing but
サラダ一皿[saradahitosara] plate of salad

安全第一[anzendaiichi] safety first
一か八か[ichikabachika] sink or swim
一っ走り[hitoppashiri] spin (as in 'take a car for a spin')
一つ一つ[hitotsuhitotsu] one-by-one

不悪[ashikarazu] don't get me wrong, but ...
意識不明[ishikifumei] unconscious
一心不乱[isshinfuran] wholeheartedly
一定不変[itteifuhen] invariable
運動不足[undoubusoku] insufficient exercise

栄養不足[eiyoubusoku] malnutrition
過不足[kafusoku] excess or deficiency
回復不可能[kaifukufukanou] non-recoverable
気不味い[kimazui] unpleasant
健康不安[kenkoufuan] poor health

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

史的唯物論[shitekiyuibutsuron] historical materialism
唯でさえ[tadadesae] even at the best of times
唯一[yuiitsu] only
唯一無二[yuiitsumuni] one and only
唯我独尊[yuigadokuson] self-conceit

唯我論[yuigaron] solipsism (phil.)
唯今[tadaima] Here I am
唯心論[yuishinron] spiritualism
唯美主義[yuibishugi] estheticism