“褪了色”常见的英文表达有 faded、discolored 或 lost its color，具体使用哪个取决于语境：
faded：最为常用，强调颜色因时间、日晒、洗涤等因素而逐渐变淡、失去原有鲜艳度，适用于衣物、织物、照片、色彩等。例如：
The old T-shirt had faded to a pale blue.（那件旧T恤已经褪成了淡蓝色。）
The walls of the house were faded from years of exposure to the sun.（房子的墙壁因多年日晒已经褪色。）
discolored：侧重于颜色发生不正常的变化，可能是由于化学作用、污染、疾病等原因导致，不一定是自然褪色。例如：
The white shirt turned discolored after being left in the washing machine with a red sock.（那件白衬衫和一只红袜子一起放在洗衣机里后，颜色变脏了/变色了 。）
The patient's skin had discolored due to a rare medical condition.（由于一种罕见的疾病，患者的皮肤变色了。）
lost its color：是比较直白的表达，意思是“失去了颜色”，适用于各种需要明确表达颜色消失的场景。例如：
The flowers in the vase had lost their color after a few days.（花瓶里的花几天后就失去了颜色。）
The paint on the old fence had lost its color and looked dull.（旧篱笆上的油漆已经褪色，看起来很暗淡。）