Noun

1. The act of gathering into a heap or mass; accumulation.
2. An excess of traffic.
3. Overfullness of the capillary and other blood vessels, etc., in any locality or organ (often producing other morbid symptoms); local hypermic, active or passive; as, arterial congestion; venous congestion; congestion of the lungs.
4. An excess of mucus or fluid in the respiratory system; congestion of the lungs, or nasal congestion.