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

蘇連[soren] (former) Soviet Union
ドイツ連邦共和国[doitsurenpoukyouwakoku] Federal Republic of Germany (former West Germany)
破天連[pateren] Portuguese Jesuits (in Japan in the 16th century)
一連[ichiren] series
引連れる[hikitsureru] to take along with

英連邦[eirenpou] Commonwealth of Nations (formerly British Commonwealth)
欧州連合[oushuurengou] European Union
家族連れ[kazokuzure] taking the family along
関連[kanren] relation
関連会社[kanrengaisha] associated company