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

向きに成る[mukininaru] to become serious
持て成し[motenashi] entertainment
成吉思汗[jingisukan] Japanese mutton and vegetable dish
亜成層圏[aseisouken] substratosphere
成す[nasu] to build up

成手[narite] candidate
育成栽培[ikuseisaibai] vegetable and fruit growing
一気呵成[ikkikasei] finishing writing, work, etc. at a stroke (stretch)
化成[kasei] change
化成工業[kaseikougyou] chemical industry

キリル文字[kirirumoji] Cyrillic character
ギリシア文字[girishiamoji] Greek character
ロシア文字[roshiamoji] Russian character
悪文[akubun] bad style
遺文[ibun] literary remains

一文[ichibun] (a) sentence
一文[ichimon] something insignificant
一文字[ichimonji] straight line
一文商い[ichimonakinai] (a) penny store
一文惜み[ichimonoshimi] stinginess

一系[ikkei] single-family lineage
家系[kakei] family lineage
革新系[kakushinkei] liberal
共産系[kyousankei] communist controlled
銀行系カード[ginkoukeikaado] bank issued credit card

系図[keizu] family tree
系図学[keizugaku] genealogy (the study)
系統[keitou] system
系統樹[keitouju] genealogical tree