Definition from Wiktionary, the free dictionary
congestion (plural congestions)
- The act of gathering into a heap or mass; accumulation.
- An excess of traffic.
- (medicine) 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.
- (medicine) An excess of mucus or fluid in the respiratory system; congestion of the lungs, or nasal congestion.
Derived terms 
act of gathering into a heap or mass
excess of traffic
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