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

小便をする[shoubenwosuru] to pee
穏便[onbin] gentle
音便[onbin] euphony
花便り[hanadayori] news of cherry blossom blooming conditions
簡便[kanben] handy

雁の便り[karinotayori] (a) letter
共同便所[kyoudoubenjo] comfort station
軽便[keiben] convenience
検便[kenben] stool (feces) examination
公衆便所[koushuubenjo] public lavatory

黄道十二宮[koudoujuunikyuu] twelve signs of the zodiac
丸十[marujuu] cross in a circle
五十音[gojuuon] the Japanese syllabary
五十音順[gojuuonjun] the syllabary order
五十三次[gojuusantsugi] the 53 Toukaidou stages

五十年祭[gojuunensai] jubilee
五十歩百歩[gojuppohyappo] six of one and a half dozen of the other
五十路[isoji] age fifty
三十戸[sanjikko] thirty houses
三十三所[sanjuusansho] any of a number of sets of thirty-three holy places enshrining Avalokitesvara (esp. those comprising a popular pilgrimage in the Kinki region)

まっ四角[masshikaku] square
一天四海[ittenshikai] the world
下四半期[shimoshihanki] last quarter (of the year)
弦楽四重奏曲[gengakushijuusoukyoku] string quartet
再三再四[saisansaishi] repeatedly

三寒四温[sankanshion] alternation of three cold and four warm days
四つ[yottsu] four
四つんばい[yotsunbai] (crawl) on all fours
四つ角[yotsukado] four corners
四つ足[yotsuashi] four-footed (animal)

オムツ気触れ[omutsukabure] diaper rash
お気の毒[okinodoku] pitiful
御天気[otenki] weather
利かん気[kikanki] daring
さり気ない[sarigenai] nonchalant

哀れ気[awarege] sad
悪気[warugi] ill will
圧搾空気[assakukuuki] compressed air
圧縮空気[asshukukuuki] compressed air
圧電気[atsudenki] piezoelectricity

おけさ節[okesabushi] style of Japanese folk song associated with Niigata Prefecture
双節棍[nunchaku] nunchaku (two linked fighting sticks)
一音節[ichionsetsu] monosyllable
一節切り[hitoyogiri] one-jointed bamboo musical instrument
音節[onsetsu] syllable

鰹節[katsubushi] katsuobushi
環節[kansetsu] segment (of worm)
関節[kansetsu] joints (knee joint, elbow joint, etc.)
関節リューマチ[kansetsuryuumachi] rheumatoid arthritis
関節炎[kansetsuen] arthritis

ローロー船[rooroofune] roll-on-roll-off ship
宇宙船[uchuusen] space ship
下船[gesen] going ashore
荷船[nibune] freighter
貨物船[kamotsusen] freighter

艦船[kansen] (ocean) vessels
汽船[kisen] steamship
客船[kyakusen] passenger boat
巨船[kyosen] ocean liner
漁船[gyosen] fishing boat

書留郵便[kakitomeyuubin] registered mail
定形郵便物[teikeiyuubinbutsu] standard size mail
年賀郵便[nengayuubin] New Year's mail
郵政省[yuuseishou] Ministry of Posts and Telecommunications
郵政大臣[yuuseidaijin] Minister of Posts and Telecommunications

郵税[yuuzei] postage
郵送[yuusou] mailing
郵送料[yuusouryou] freight costs
郵袋[yuutai] mailbag
郵便為替[yuubinkawase] postal money order