Thayer's Greek Lexicon

 1. a reward for good tidings
2. good tidings
  1) the glad tidings of the kingdom of God soon to be set up, and
subsequently also of Jesus the Messiah, the founder of this
kingdom. After the death of Christ, the term comprises also
the preaching of (concerning) Jesus Christ as having suffered
death on the cross to procure eternal salvation for the men in
the kingdom of God, but as restored to life and exalted to the
right hand of God in heaven, thence to return in majesty to
consummate the kingdom of God
  2) the glad tidings of salvation through Christ
  3) the proclamation of the grace of God manifest and pledged in Christ
  4) the gospel
  5) as the messianic rank of Jesus was proved by his words, his
deeds, and his death, the narrative of the sayings, deeds, and
death of Jesus Christ came to be called the gospel or glad tidings