Thayer's Greek Lexicon

 1. in Greek writings, an interpreter of oracles or of other hidden things
2. one who, moved by the Spirit of God and hence his organ or
spokesman, solemnly declares to men what he has received by
inspiration, especially concerning future events, and in
particular such as relate to the cause and kingdom of God and to
human salvation
  1) the OT prophets, having foretold the kingdom, deeds and death,
of Jesus the Messiah.
  2) of John the Baptist, the herald of Jesus the Messiah
  3) of the illustrious prophet, the Jews expected before the advent
of the Messiah
  4) the Messiah
  5) of men filled with the Spirit of God, who by God's authority
and command in words of weight pleads the cause of God and
urges salvation of men
  6) of prophets that appeared in the apostolic age among Christians
2f1. they are associated with the apostles
2f2. they discerned and did what is best for the Christian
cause, foretelling certain future events. (Acts 11:27.
2f3. in the religious assemblies of the Christians, they were
moved by the Holy Spirit to speak, having power to
instruct, comfort, encourage, rebuke, convict, and
stimulate, their hearers
3. a poet (because poets were believed to sing under divine
inspiration)
  1) of Epimenides (Tit. 1:12.