usage: weakening in force or intensity; "attenuation in the volume of the sound"
Verb
1. fade, melt, weaken
usage: become less clearly visible or distinguishable; disappear gradually or seemingly; "The scene begins to fade"; "The tree trunks are melting into the forest at dusk"
2. fade, wither, disappear, vanish, go away
usage: lose freshness, vigor, or vitality; "Her bloom was fading"