An Aramaic word meaning "father," transliterated directly into Greek. While Greek had its own word for father (patēr, G3962), abba preserves an intimate, familial address — closer to "Daddy" or "Papa" than a formal "Father." It occurs three times in the New Testament: twice in Paul's epistles and once on the lips of Jesus in Gethsemane.
Abba is one of the most explosive words in the New Testament. Jesus addressed God with Abba in the darkest hour of His suffering (Mark 14:36), revealing the intimacy of His relationship with the Father. Paul declares that the Holy Spirit, given to believers, cries out this same word in their hearts — "Abba, Father!" — confirming their adoption as God's own children (Romans 8:15; Galatians 4:6). This word shatters distance. The God before whom angels veil their faces is the One who invites redeemed sinners to cry "Daddy." That is grace.