Definitions of Lady:

• noun:   a woman of the peerage in Britain
• noun:   a polite name for any woman

  Example: "A nice lady at the library helped me"

• noun:   a woman of refinement

  Example: "A chauffeur opened the door of the limousine for the grand lady"

• name:  A female given name (rare: 1 in 50000 females; popularity rank in the U.S.: #2508)
• name:  A surname (rare: 1 in 100000 families; popularity rank in the U.S.: #11510)