How would someone describe congestive heart failure?

Excess fluid. Congestive heart failure is when the heart is not able to pump as it would normally, and extra fluid can accumulate in the lungs or legs, depending on the type of congestive heart failure.
Syndrome. CHF is syndrome in which one retains fluid in the lungs and/or feet resulting in fatigue, breathlessness, difficulty breathing when lying down, swelling, and weight gain. There are many causes but the common thread is that the heart isn't performing up to par.