Thayer's Greek Lexicon

 1. to be a herald, to officiate as a herald
  1) to proclaim after the manner of a herald
  2) always with the suggestion of formality, gravity and an
authority which must be listened to and obeyed
2. to publish, proclaim openly: something which has been done
3. used of the public proclamation of the gospel and matters
pertaining to it, made by John the Baptist, by Jesus, by the
apostles and other Christian teachers