the third person in the Trinity; Jesus promised the Apostles that he would send the Holy Spirit after his Crucifixion and Resurrection; it came on Pentecost
The person (hypostasis) of the Trinity or Godhead corresponding to divine essence present in the faithful (particularly inspired prophets) and considered to proceed either from (Eastern Orthodoxy) God the Father alone or (Roman Catholicism) from Him together with God the Son.
The spirit of God, especially in its inspiration of prophets and quickening of fetuses.