Thayer's Greek Lexicon

 1. generator or male ancestor
  1) either the nearest ancestor: father of the corporeal
nature, natural fathers, both parents
  2) a more remote ancestor, the founder of a race or tribe,
progenitor of a people, forefather: so Abraham is called,
Jacob and David
1b1. fathers i.e. ancestors, forefathers, founders of a race
  3) one advanced in years, a senior
2. metaph.
  1) the originator and transmitter of anything
2a1. the authors of a family or society of persons animated by
the same spirit as himself
2a2. one who has infused his own spirit into others, who
actuates and governs their minds
  2) one who stands in a father's place and looks after another
in a paternal way
  3) a title of honour
2c1. teachers, as those to whom pupils trace back the knowledge
and training they have received
2c2. the members of the Sanhedrin, whose prerogative it was by
virtue of the wisdom and experience in which they excelled,
to take charge of the interests of others
3. God is called the Father
  1) of the stars, the heavenly luminaries, because he is their
creator, upholder, ruler
  2) of all rational and intelligent beings, whether angels or
men, because he is their creator, preserver, guardian and
protector
3b1. of spiritual beings and of all men
  3) of Christians, as those who through Christ have been
exalted to a specially close and intimate relationship with
God, and who no longer dread him as a stern judge of
sinners, but revere him as their reconciled and loving Father
  4) the Father of Jesus Christ, as one whom God has united to
himself in the closest bond of love and intimacy, made
acquainted with his purposes, appointed to explain and carry
out among men the plan of salvation, and made to share also
in his own divine nature
3d1. by Jesus Christ himself
3d2. by the apostles