stagnant

Not flowing or moving, and often foul-smelling or stale.

Showing little or no activity or vitality; inactive or sluggish.

That stagnates; not flowing; not running in a current or steam; motionless; hence, impure or foul from want of motion.

Not active or brisk; dull.

Lacking freshness, motion, flow, progress, or change; stale; motionless; still.