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

御姉さん[oneesan] elder sister
義姉[gishi] sister-in-law (elder)
兄姉[keishi] brother and sister
姉さん[neesan] elder sister
姉貴[aneki] elder sister

姉御[anego] elder sister
姉上[aneue] older sister
姉弟[shitei] older sister and younger brother
姉妹会社[shimaigaisha] affiliated companies

御兄弟[gokyoudai] siblings
愛弟子[manadeshi] favorite pupil
義弟[gitei] younger brother-in-law
兄弟[kyoudai] siblings
兄弟愛[kyoudaiai] brotherly love

兄弟子[anideshi] senior schoolmate
兄弟分[kyoudaibun] buddy
再従弟[saijuutei] younger second cousin
姉弟[shitei] older sister and younger brother
子弟[shitei] young(er) people

パートタイム従業員[paatotaimujuugyouin] part time employee
フルタイム従業員[furutaimujuugyouin] full-time employee
阿諛追従[ayutsuishou] excessive flattery
家従[kajuu] steward
郷に入っては郷に従え[gouniittehagounishitagae] when in Rome, do as the Romans do

屈従[kutsujuu] servile submission
合従連衡[gasshourenkou] alliance (of the Six Kingdoms against the Qin dynasty, and of individual Kingdoms with the Qin dynasty)
再従兄[saijuukei] elder second cousin
再従弟[saijuutei] younger second cousin
侍従[jijuu] chamberlain