Definitions of then:

• noun:   that time; that moment

  Example: "We will arrive before then"

• adverb:   subsequently or soon afterward (often used as sentence connectors)

  Example: "Then he left"

• adverb:   at that time

  Example: "I was young then"

• adverb:   in that case or as a consequence

  Example: "If he didn't take it, then who did?"

• name:  A surname (very rare: popularity rank in the U.S.: #21184)