Dictionary entry

Ἀββά

G. Abbott-Smith's A Manual Greek Lexicon of the New Testament with Strong's

Ἀββά (T, -ᾶ), indecl. (Aram, אַבָּא, emphatic form of אַב = Heb. אָב, father),

used in the phrase Ἀ. ὁ παήρ, Abba, Father (v. Swete on Mk 14:36): Mk 14:36, Ro 8:15, Ga 4:6.†