One often hears over the pulpit (both LDS and non) that Jesus referred to God the Father in Mark 14:36 (cf. Gal. 4:6 and Romans 8: 15) with the word Abba, which is taken to be a familial diminutive and thus having the connotation of something like “daddy, papa.” I remember that when I first heard this idea, it appealed to me. It had a certain plausibility; the word for “father” in Hebrew/Aramaic is Ab (pronounced Av), and it is common enough to form a diminutive by an added syllable (as in papa itself). Indeed, abba in modern Hebrew is used as a familial diminutive. And I liked the idea of the possible intimacy suggested by the posited nuance to the word.
It’s a cool idea. Unfortunately, it is pretty unlikely. In each of its three appearances in the NT, it is rendered by the Greek ho patEr, lit. “the father,” and not the vocative pater, suggesting that the NT writers saw it as a determinative form: ‘abba’. Such determinative forms are frequently used in Aramaic and Hebrew when a vocative is required. Thus, the form is a determinative “the father,” which is used in the place of a vocative in direct address “O father.”
See the article “Abba” in the Anchor Bible Dictionary, and an article with a great title: J. Barr, “‘Abba’ Isn’t ‘Daddy’,” Journal of Theological Studies 39 (1988): 28-47.