the fact of no longer developing or making progress (Oxford)
the fact of not moving and therefore smelling unpleasant (Oxford)
to stay the same and not grow or develop (Cambridge)
Country is in a period of economic stagnation. (Oxford)
My music career had stagnated. (Cambridge)
economic stagnation
a stagnant Career
Sluggishness
Immovable
Boom
Rise
Stagnation
Stagnant