fade_out
1. [ verb ] become weaker, as of sound or vision
Synonyms: dissolve fade_away
Examples:

"The sound faded out"

Related terms: change_state dissolve receding
2. [ verb ] become less clearly visible or distinguishable; disappear gradually or seemingly
Synonyms: fade melt
Examples:

"The scene begins to fade" "The tree trunks are melting into the forest at dusk"

Related terms: weaken fade
Similar spelling:   fadeout