alive, colorful:
dispirited,
dull,
colorless,
inactive,
pale,
lifeless,
weak,
lazy,
sluggish,
lethargic,
idle,
apathetic,
quiet.
noun:
faint,
thin,
inactive,
murmurous,
soft,
muted,
nonresonant,
tinny,
smothered,
unreverberant,
colourless,
cavernous,
weak,
hollow.