Definitions of third:

• noun:   the musical interval between one note and another three notes away from it

  Example: "A simple harmony written in major thirds"

• noun:   following the second position in an ordering or series

  Example: "A distant third"

• noun:   the fielding position of the player on a baseball team who is stationed near 3rd base

  Example: "He is playing third"

• noun:   the base that must be touched third by a base runner in baseball

  Example: "He was cut down on a close play at third"

• noun:   the third from the lowest forward ratio gear in the gear box of a motor vehicle

  Example: "You shouldn't try to start in third gear"

• noun:   one of three equal parts of a divisible whole

  Example: "It contains approximately a third of the minimum daily requirement"

• adjective:   coming next after the second and just before the fourth in position
• adverb:   in the third place

  Example: "Third we must consider unemployment"