iron color; dark metallic hue
Describes a dark, metallic color reminiscent of iron: can be reddish-black, greenish-black, iron blue, or steel gray depending on context. Often used for describing objects, fabrics, or natural phenomena.
He was wearing an iron-gray suit.
鉄色の雲が空を覆っている。
Iron-colored clouds are covering the sky.
Compound of 鉄 (iron) and 色 (color). The exact historical derivation is straightforward; the word has been used to describe the characteristic dark, metallic hue of iron.