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

御化け[obake] goblin
御化け屋敷[obakeyashiki] haunted house
胡麻化し[gomakashi] hanky-panky
イオン化[ionka] ionization
カスタム化[kasutamuka] customization

コンピュータ化[konpyuutaka] computerization
シアン化合物[shiankagoubutsu] cyanide
シアン化物[shiankabutsu] cyanide
スリム化[surimuka] thinning
パーソナル化[paasonaruka] personalization

螟蛾[meiga] pyralid (any moth of family Pyralidae, many of which have larvae that devour foodstuffs)
誘蛾灯[yuugatou] light trap for killing insects
毒蛾[dokuga] poisonous moth
夜盗蛾[yotouga] cabbage armyworm
衣蛾[iga] Tinea translucens (species of clothes moth)

黄色雀蛾[kiirosuzume] yellow hawk moth
灯蛾[hitoriga] garden tiger moth (Arctia caja)
尺蛾[shakuga] geometer moth
蚕蛾[kaikoga] silkworm moth

螟蛾[meiga] pyralid (any moth of family Pyralidae, many of which have larvae that devour foodstuffs)
螟虫[zuimushi] pyralid larva
一点大螟蛾[ittenoomeiga] yellow stem borer (species of moth, Scirpophaga incertulas)
三化螟蛾[sankameiga] yellow stem borer (species of moth, Scirpophaga incertulas)

二化螟蛾[nikameiga] striped stem borer (species of moth, Chilo suppressalis)
稲の螟虫[inenozuimushi] striped stem borer larva
螟蛉[meirei] hornworm