Abba, in Aramaic, is NOT "Dad," So much for Jesus calling God "Dad."

Post Vatican II doctrine holds that a salient aspect of Jesus' radicalism was that he had the audacity to call G-d "Dad."

This hypothesis is based on the recognition that אבא means Dad.  In modern Hebrew.

So, assuming post-Vatican II doctrine is correct, not only was Jesus audaciously radical, he was linguistically 2000 years ahead of his time.

However, if one assumes that Jesus was speaking Aramaic (which is generally supposed to have been the vernacular of the period and location), אבא, in Aramaic means "the father."

Aramaic, while using Hebrew letters, has something of a different grammatical structure:  in Hebrew the definite article  הַ  is attached to the noun as a prefix. In Aramaic, the definite article is א and it is attached to the noun as a suffix.

Thus in Hebrew "the father" would be האב, while in Aramaic, it would be אבא.

This is also consistent with social practice of the era--the male parent, as owner, lord and master of his family, was not generally treated with familiarity--that radical shift in familial behaviour was a creation of the 20 century, following the adoption of universal sufferage.  In the ancient world, the male parent (immanent as well as transcendent) was understood to be owner, lord and master of his domicile/domain, and that primacy was unquestioned.  Until the advent of universal sufferage.