ちょっと一杯[chottoippai] let's have a quick drink
ばつ一[batsuichi] being once divorced
一向[hitaburu] nothing but
サラダ一皿[saradahitosara] plate of salad

安全第一[anzendaiichi] safety first
一か八か[ichikabachika] sink or swim
一っ走り[hitoppashiri] spin (as in 'take a car for a spin')
一つ一つ[hitotsuhitotsu] one-by-one

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

御誕生日おめでとうございます[otanjoubiomedetougozaimasu] Happy Birthday
また明日[mataashita] see you tomorrow
旭日[kyokujitsu] rising sun
旭日昇天[kyokujitsushouten] full of vigor and vitality (like the rising sun) (vigour)
或日[aruhi] one day (e.g. "one day while studying, ..")

一日の長[ichijitsunochou] superiority
一日一日[ichinichiichinichi] gradually
一日一夜[ichinichiichiya] all day and night
一日増しに[ichinichimashini] day by day
一日置き[ichinichioki] every other day