unfadable
adjective
un·fad·able
¦ən¦fādəbəl
1
: not subject to fading : fast, everlasting
a fabric of unfadable color
2
: incapable of being forgotten : memorable, deathless
an unfadable act of political courage 
Manchester Guardian Weekly
Manchester Guardian Weekly
Word History
Etymology
un- entry 1 + fade + -able