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

御付き[otsuki] retainer
御墨付き[osumitsuki] handwriting
恰好付ける[kakkoutsukeru] to affect a stylish air
食っ付く[kuttsuku] to adhere to
食っ付ける[kuttsukeru] to attach

しがみ付く[shigamitsuku] to cling
何方付かず[docchitsukazu] gray area
に付いて[nitsuite] concerning
に付き[nitsuki] because of
打っ付ける[uchitsukeru] to knock

イスラム原理主義[isuramugenrishugi] Islamic fundamentalism
海原[unabara] ocean
関数原型[kansuugenkei] function prototype
基本原理[kihongenri] fundamental idea

機雷原[kiraigen] minefield
規格原案[kikakugenan] standards draft
桑原桑原[kuwabarakuwabara] charm to ward off lightning and misfortune
権原[kengen] origin of rights

亜種[ashu] subspecies
異機種[ikishu] heterogenous equipment
異種[ishu] different kind (species, variety)
育種[ikushu] (plant) breeding
育種家[ikushuka] (plant) breeder

育種所[ikushujo] (plant) nursery
一種[isshu] species
一粒種[hitotsubudane] an only child
種違い[tanechigai] half-brother
艶種[tsuyadane] love affair