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

杏林[kyourin] apricot grove
営林[eirin] forest management
営林署[eirinsho] forest service field office
花林[karin] Burmese rosewood (Pterocarpus indicus)
花林糖[karintou] fried dough cake

寒帯林[kantairin] taiga
翰林[kanrin] literary circles
翰林院[kanrinin] academy
原始林[genshirin] primeval forest
原生林[genseirin] primeval forest

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-