stag·nant 
(stăgnənt)
(stăgnənt)adj.
1. Not flowing or moving, and often foul-smelling or stale: stagnant ponds; stagnant air.
2. Showing little or no activity or vitality; inactive or sluggish: a stagnant economy; a stagnant mind.
[Latin stāgnāns, stāgnant-, present participle of stāgnāre, to be stagnant; see STAGNATE.]
stagnan·cy n.
stagnant·ly adv.