Definitions of loud:

• adjective:   characterized by or producing sound of great volume or intensity

  Example: "A group of loud children"

• adjective:   used chiefly as a direction or description in music
• adjective:   tastelessly showy

  Example: "Loud sport shirts"

• adverb:   with relatively high volume

  Example: "The band played loudly"

• name:  A surname (very rare: popularity rank in the U.S.: #19077)