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

アセンブリー言葉[asenburiikotoba] assembly language
一葉[ichiyou] one leaf
右葉[uyou] right lobe
押し葉[oshiba] pressed leaves
観葉植物[kanyoushokubutsu] decorative plant

棄言葉[sutekotoba] sharp parting remark
京葉[keiyou] Tokyo and Chiba
言葉[kotoba] language
言葉づかい[kotobazukai] speech
口言葉[kuchikotoba] spoken language