In severe cases, the viral infection causes a high fever, bleeding into the skin, and necrosis (death) of cells in the kidney and liver. The damage done to the liver from the virus results in severe jaundice which yellows the skin. Hence, the yellow in yellow fever..
filter definition: The definition of a filter is something that separates solids from liquids, or eliminates impurities, or allows only certain things to pass through. (noun) A Brita that you attach to your water faucet to remove impurities from you...
Filtering is the removal of all visual particles and matter from the water such as dirt, leaves, insects, etc so it can be properly purified and then safely consumed. Purifying is the removal of all invisible bacteria, germs and other harmful elements from the water so it can be safely consumed.