the outer covering of the body. The skin is the largest organ of the body, and it performs a number of vital functions. It serves as a protective barrier against microorganisms. It helps shield the delicate, sensitive tissues underneath from mechanical and other injuries.
The definition of a direct primary election is when people vote for candidates of their political party by direct vote instead of by delegates at a convention.
A primary source is one that was written/drawn/taken by someone around the time of the event. A secondary source is one that was created some time after the event, by someone who wasn't there but researched it, e.g. a source from a textbook or a historian.