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

医学技術士[igakugijutsushi] medical technician
医学士[igakushi] Bachelor of Medicine
一言居士[ichigenkoji] person who is ready to comment on every subject
一士[isshi] private first-class (JSDF)
隠士[inshi] hermit

宇宙飛行士[uchuuhikoushi] astronaut
運転士[untenshi] driver
栄養士[eiyoushi] nutritionist
下士[kashi] noncommissioned officer
下士官[kashikan] non-commissioned officer