noun, noun which may take the genitive case particle 'no'
A deep, rich shade of green, often used to describe natural colors like deep forest green or dark green fabrics.
彼女は濃緑色のドレスを着ていた。
She wore a dark green dress.
この濃緑色の葉はとても美しい。
These dark green leaves are very beautiful.
暗緑色 means 'dark green' with a nuance of dullness or lack of brightness, whereas 濃緑色 emphasizes depth and richness of the green hue.
Compound of 濃 (dark, deep) + 緑 (green) + 色 (color). The reading のうりょくしょく follows standard on'yomi readings for the kanji.