Greek: αββα [abba] (Noun). Aramaic word signifying "father".

αββα [abba] appears 3 times in the NT:

(1) Mark 14: 36
And he said, Abba, Father, all things are possible unto thee; take away this cup from me: nevertheless not what I will, but what thou wilt.

(2) Romans 8: 15
For ye have not received the spirit of bondage again to fear; but ye have received the Spirit of adoption, whereby we cry, Abba, Father.

(3) Galatians 4: 6
And because ye are sons, God hath sent forth the Spirit of his Son into your hearts, crying, Abba, Father.