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

助番[sukeban] leader of a female gang
ブロック番号[burokkubangou] block number
暗唱番号[anshoubangou] personal identification number
一貫番号[ikkanbangou] serial number
一番[ichiban] best

一番[hitotsugai] pair
一番鶏[ichibandori] first cockcrowing
一番手[ichibante] first player
一番乗り[ichibannori] leader of a charge
一番線[ichibansen] track no. 1

アルファ線[arufasen] alpha rays
エックス線[ekkususen] X-ray
サイン曲線[sainkyokusen] sinusoid
スピード線[supiidosen] speed lines
緯線[isen] parallel

一次線輪[ichijisenrin] primary coil
一線[issen] line
一直線[icchokusen] straight line
一番線[ichibansen] track no. 1
一塁線[ichiruisen] first-base line