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

幻を追う[maboroshiwoou] to pursue an illusion
幻影[genei] phantom
幻覚[genkaku] hallucination
幻覚剤[genkakuzai] hallucinogen
幻姿[genshi] apparition

幻視[genshi] visual hallucination
幻想[gensou] illusions
幻想劇[gensougeki] non-realistic drama
幻像[genzou] phantom