Faded things have lost the bright color they once had. Your faded jeans, once dark blue but now pale and worn, might be your favorite thing to wear.
Clothes become faded after being worn and washed again and again, and in many places the landscape itself seems faded in the wintertime, all dull grays and pale browns. Strength, energy, or vitality can also become faded, like a boxer toward the end of a long match. The Old French root of faded is fader, "become weak," from fade, "weak, pale, or insipid."