This is the 5291st most frequent Japanese word.
brown
The Japanese word for "brown" is 茶色 (cha-iro), meaning a color resembling that of tea.
茶色 (brown) is used here as an adjective to describe a characteristic (the hair).
彼女は茶色い髪を持っています。
She has brown hair.
茶色 (brown) functions as a noun here to indicate the color of the subject (the eyes).
その猫の目は茶色です。
The cat's eyes are brown.
茶色 (brown) is used as a color name (noun) in the tool or material context (the paint).