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

ゼロ次[zeroji] zero-order
位次[iji] order of rank
一次[ichiji] first
一次記憶[ichijikioku] first memory
一次元[ichijigen] one dimensional

一次線輪[ichijisenrin] primary coil
一次電流[ichijidenryuu] primary current
月次[tsukinami] every month
五十三次[gojuusantsugi] the 53 Toukaidou stages
高次[kouji] higher-order-

印池[inchi] seal stamp pad
乾電池[kandenchi] dry cell
古池[furuike] old pool
光電池[koudenchi] photocell
湿電池[shitsudenchi] wet cell battery

酒池肉林[shuchinikurin] sumptuous feast
人工池[jinkouike] artificial pool
蓄電池[chikudenchi] storage battery
貯水池[chosuichi] reservoir

アドオン電話[adoondenwa] add-on telephone
コードレス電話[koodoresudenwa] cordless phone
テレビ電話[terebidenwa] visual telephone
圧電気[atsudenki] piezoelectricity
圧電効果[atsudenkouka] piezoelectric effect

異方導電フィルム[ihoudoudenfirumu] oriented conduction film
異方導電膜[ihoudoudenmaku] oriented conduction film
一次電流[ichijidenryuu] primary current
印加電圧[inkadenatsu] applied voltage