一円[ichien] one yen
一円玉[ichiendama] one-yen coin
一円札[ichiensatsu] one-yen bill
円か[madoka] round
円やか[maroyaka] round

円グラフ[engurafu] pie graph
円安[enyasu] cheap yen
円為替[engawase] yen exchange
円域[eniki] yen bloc

お歯黒[ohaguro] tooth blackening
暗黒期[ankokuki] eclipse period
暗黒時代[ankokujidai] Dark Ages
暗黒大陸[ankokutairiku] Dark Continent (i.e. Africa)
黒い[kuroi] black

黒い霧[kuroikiri] thick fog
黒くする[kurokusuru] to blacken
黒ずむ[kurozumu] to blacken
黒っぽい[kuroppoi] dark