Definition of "Stagnate" :

verb: be idle; exist in a changeless situation

"The old man sat and stagnated on his porch."

verb: cease to flow; stand without moving

"Blood stagnates in the capillaries."

verb: cause to stagnate

"There are marshes that stagnate the waters."

verb: stand still

"Industry will stagnate if we do not stimulate our economy."