Thayer's Greek Lexicon

 1. elder, of age,
  1) the elder of two people
  2) advanced in life, an elder, a senior
1b1. forefathers
2. a term of rank or office
  1) among the Jews
2a1. members of the great council or Sanhedrin (because in
early times the rulers of the people, judges, etc., were
selected from elderly men)
2a2. of those who in separate cities managed public affairs and
administered justice
  2) among the Christians, those who presided over the assemblies
(or churches) The NT uses the term bishop, elders, and
presbyters interchangeably
  3) the twenty four members of the heavenly Sanhedrin or court
seated on thrones around the throne of God