Definitions of folk:

• noun:   people in general

  Example: "They're just country folk"

• noun:   a social division of (usually preliterate) people
• noun:   the traditional and typically anonymous music that is an expression of the life of people in a community
• noun:   people descended from a common ancestor
• name:  A surname (rare: 1 in 50000 families; popularity rank in the U.S.: #4855)