Definitions of stagnate:

• verb:   cease to flow; stand without moving

  Example: "Blood stagnates in the capillaries"

• verb:   cause to stagnate

  Example: "There are marshes that stagnate the waters"

• verb:   stand still

  Example: "Industry will stagnate if we do not stimulate our economy"

• verb:   be idle; exist in a changeless situation

  Example: "The old man sat and stagnated on his porch"