雄牛[oushi] bull
牡牛座[oushiza] Taurus (constellation)
乾燥牛乳[kansougyuunyuu] powdered milk
牛脂[gyuushi] beef tallow
牛飼い[ushikai] cattleman

牛耳る[gyuujiru] to control
牛舎[gyuusha] cow shed
牛車[gyuusha] ox carriage (for Heian era nobles)
牛小屋[ushigoya] cow shed

井の中の蛙大海を知らず[inonakanokawazutaikaiwoshirazu] parochial
雨蛙[amagaeru] tree frog (esp. the Japanese tree frog, Hyla japonica)
蛙の子は蛙[kaerunokohakaeru] like father, like son
蛙跳び[kaerutobi] (game of) leapfrog
殿様蛙[tonosamagaeru] black-spotted pond frog (Rana nigromaculata)

蟇蛙[hikigaeru] toad (esp. the Japanese toad, Bufo japonicus)
蛙又[kaerumata] curved wooden support on top of the main beam of a house, now mainly decorative (shape evocates an open-legged frog)
青蛙[aogaeru] green (tree) frog
赤蛙[akagaeru] any brown or reddish-brown frog (esp. of family Ranidae)